feat(renderer): wire remaining stubbed commands and rebuild

The v5.0.0 React UI shipped with a working surface but had a number of
features left as 'wired in a later phase' or broken by missing IPC
plumbing. This commit completes the wiring end-to-end and proves the
behaviour with the run-desktop driver.

Toolbar format buttons (Toolbar.tsx)
  - Bold, Italic, Unordered/Ordered list, Code, Link now dispatch real
    commands instead of being permanently disabled.

New module: src/renderer/lib/editor-commands.ts
  - Module-level singleton holding the active CodeMirror EditorView.
  - toggleBold/Italic/Code/CodeBlock, toggleUnorderedList/OrderedList,
    insertLink, setHeadingLevel, scrollToLine, undo, redo, insertSnippet.
  - CodeMirrorEditor mounts the view via setActiveView on mount and
    nulls it on unmount, so commands land on the focused buffer.

register-menu-commands.ts
  - file.confirmClose: prompts before closing a dirty tab via the
    confirm modal; otherwise closes silently.
  - app.quit: prompts before quitting if any buffer is dirty; uses
    the new ipc.app.quit channel.
  - short-cuts.show: shows the keyboard shortcut list in a confirm dialog.
  - editor.bold/italic/code/list.*/link/undo/redo/heading.*: drive the
    active editor.
  - find.toggle: dispatches mc:find-toggle for any listening component.
  - view.sidebarPanel/bottomPanel: navigate between sidebar sections
    via the new data-testid buttons; bottom panel toggles the REPL.
  - font.size: increase/decrease/reset on editorFontSize (10..28).
  - theme.loadCustomCss/clearCustomCss: pick and clear the custom CSS
    path on the settings store.
  - template.load: inserts a bundled markdown skeleton at the cursor.
  - print.preview/previewStyled: emit mc:print and mc:print-preview.
  - file.clearRecent: clears open tabs.
  - file.new: creates an untitled buffer and tab.
  - editor.gotoHeading: scrolls to a given line (used by Outline and
    Breadcrumb).
  - view.toggleSidebar: already wired.
  - file.opened: already wired (prior fix).

Sidebar Outline + Breadcrumb
  - Both now click through to 'editor.gotoHeading' with the line
    number extracted from the active buffer.
  - Sidebar exposes data-testid for the 'view.sidebarPanel' menu action.

editor-commands sets the active view; scroll metrics flow through to
Minimap which now reads scrollRatio/visibleRatio from the editor.

Export dialogs (PDF/DOCX/HTML)
  - Replaced the broken ipc.export.{pdf,docx,html,batch} calls (those
    channels were not implemented in main and only CHANNEL_MISSING
    was returned) with renderer-side pipelines.
  - PDF: generateHtml() with @page CSS for size + margins, then
    ipc.print to the main process for native print-to-PDF.
  - DOCX: generateDocx() from the existing lib, then ipc.file.writeBuffer.
  - HTML: generateHtml() then ipc.file.writeBuffer.
  - All three dialogs use ipc.app.showSaveDialog for output path
    (new IPC handler) and ipc.file.writeBuffer for the binary write
    (new preload channel).
  - PrintPreview now uses MarkdownRenderer instead of a raw <pre>.

New settings fields
  - editorFontSize: 10..28 px (drives CodeMirror theme font-size)
  - customCssPath: string|null (Theme menu wires 'load-custom-css' and
    'clear-custom-css' to it).

New IPC channels
  - 'app:quit', 'app:open-external', 'app:show-save-dialog',
    'write-buffer' (already existed; now exposed in preload).

Tests
  - Updated Toolbar test: format buttons are no longer disabled and
    dispatch their command ids.
  - Updated Export*D*Dialog tests to mock the new ipc surface
    (ipc.print, ipc.app.showSaveDialog, ipc.file.writeBuffer) and
    assert the new flow.
  - Updated PrintPreview test to use ipc.print.doPrint.
  - Updated phase8-toasts integration: PDF flow now goes through
    ipc.print and asserts 'Sent <title> to printer'.
  - register-menu-commands test: re-register 'template.load' AFTER
    Harness renders so the captured-args handler is the live one.

Verification
  - npm run build:renderer: success (1.6s)
  - npx vitest run: 308 passed (up from 305; 3 new + unchanged)
  - npx jest: 189 passed (unchanged)
  - .claude/skills/run-desktop/verify-features.mjs: drove the live app
    via Playwright, exercised every wired feature end-to-end, captured
    11 screenshots. All verified working (editor + preview render the
    file content, toolbar buttons dispatch, dialogs open, theme
    toggles, outline shows headings, italic button works in editor).

src/renderer/lib/commands/register-menu-commands.ts

@@ -3,16 +3,45 @@ import { useCommandStore } from '@/stores/command-store';
 import { useFileStore } from '@/stores/file-store';
 import { useAppStore } from '@/stores/app-store';
 import { useSettingsStore } from '@/stores/settings-store';
+import { useEditorStore } from '@/stores/editor-store';
+import { usePreviewStore } from '@/stores/preview-store';
 import { useMenuAction } from '@/hooks/use-menu-action';
+import {
+  toggleBold,
+  toggleItalic,
+  toggleCode,
+  toggleUnorderedList,
+  toggleOrderedList,
+  insertLink,
+  scrollToLine,
+  undo,
+  redo,
+  insertSnippet,
+  setHeadingLevel,
+} from '@/lib/editor-commands';
+import { ipc } from '@/lib/ipc';
+import { toast } from '@/lib/toast';
+import { extractHeadings, type HeadingItem } from '@/lib/headings';
+
+type OpenModal = ReturnType<typeof useAppStore.getState>['openModal'];
+
+function confirmCloseFlow(closeTab: (id: string) => void) {
+  return (tabId: string) => {
+    const buffer = useEditorStore.getState().buffers.get(tabId);
+    if (!buffer || !buffer.dirty) {
+      closeTab(tabId);
+      return;
+    }
+    useAppStore.getState().openModal('confirm', {
+      title: 'Discard unsaved changes?',
+      body: `"${buffer.path.split('/').pop() ?? buffer.path}" has unsaved edits. Close without saving?`,
+      confirmLabel: 'Discard & close',
+      destructive: true,
+      onConfirm: () => closeTab(tabId),
+    });
+  };
+}
 
-/**
- * Register all Phase 6 menu commands in the command store, and bridge
- * the native menu IPC channels to the matching command ids.
- *
- * Phase 6 scope: file/view/tab commands with direct store mappings.
- * Phase 7+ will add the dialog-driven commands (export, settings, etc.)
- * once the corresponding modals exist.
- */
 export function registerMenuCommands(): void {
   const { registerMany } = useCommandStore.getState();
 
@@ -20,6 +49,26 @@ export function registerMenuCommands(): void {
     'settings.open': () => useAppStore.getState().openModal('settings'),
     'help.about': () => useAppStore.getState().openModal('about'),
     'help.welcome': () => useAppStore.getState().openModal('welcome'),
+    'shortcuts.show': () => {
+      const open: OpenModal = useAppStore.getState().openModal;
+      open('confirm', {
+        title: 'Keyboard shortcuts',
+        body: [
+          'Open file — ⌘/Ctrl+O',
+          'Open folder — ⌘/Ctrl+Shift+O',
+          'Save — ⌘/Ctrl+S',
+          'Close tab — ⌘/Ctrl+W',
+          'Next/prev tab — ⌘/Ctrl+Tab / +Shift+Tab',
+          'Toggle sidebar — ⌘/Ctrl+B',
+          'Toggle preview — ⌘/Ctrl+Shift+P',
+          'Zen mode — ⌘/Ctrl+K then Z',
+          'Find — ⌘/Ctrl+F',
+        ].join('\n'),
+        confirmLabel: 'Got it',
+        cancelLabel: 'Close',
+        onConfirm: () => undefined,
+      });
+    },
     'file.exportPdf': () => {
       const activeTabId = useFileStore.getState().activeTabId;
       if (!activeTabId) return;
@@ -41,10 +90,29 @@ export function registerMenuCommands(): void {
       useAppStore.getState().openModal('export-batch', { sourcePaths: paths });
     },
     'file.confirmClose': () => {
-      /* stub — wired in later phase */
+      const { activeTabId, closeTab } = useFileStore.getState();
+      if (activeTabId) confirmCloseFlow(closeTab)(activeTabId);
     },
     'app.quit': () => {
-      /* stub — wired in later phase */
+      const dirty = Array.from(useEditorStore.getState().buffers.values()).filter((b) => b.dirty);
+      const quit = () => {
+        if (window.electronAPI?.app?.quit) {
+          void window.electronAPI.app.quit();
+        } else {
+          window.close();
+        }
+      };
+      if (dirty.length === 0) {
+        quit();
+        return;
+      }
+      useAppStore.getState().openModal('confirm', {
+        title: 'Unsaved changes',
+        body: `You have ${dirty.length} file${dirty.length === 1 ? '' : 's'} with unsaved changes. Quit anyway?`,
+        confirmLabel: 'Quit anyway',
+        destructive: true,
+        onConfirm: quit,
+      });
     },
     'tools.ascii': () => useAppStore.getState().openModal('ascii-generator'),
     'tools.table': () => useAppStore.getState().openModal('table-generator'),
@@ -68,6 +136,127 @@ export function registerMenuCommands(): void {
     'git.refresh': () => {
       if (typeof window !== 'undefined') window.dispatchEvent(new CustomEvent('mc:git-refresh'));
     },
+
+    // Editor format commands — drive the active CodeMirror view.
+    'editor.bold': () => toggleBold(),
+    'editor.italic': () => toggleItalic(),
+    'editor.code': () => toggleCode(),
+    'editor.list.unordered': () => toggleUnorderedList(),
+    'editor.list.ordered': () => toggleOrderedList(),
+    'editor.link': () => insertLink(),
+    'editor.undo': () => undo(),
+    'editor.redo': () => redo(),
+    'editor.heading.1': () => setHeadingLevel(1),
+    'editor.heading.2': () => setHeadingLevel(2),
+    'editor.heading.3': () => setHeadingLevel(3),
+    'editor.heading.paragraph': () => setHeadingLevel(0),
+
+    // Find / replace — focus the editor and let CodeMirror's `search` extension
+    // handle the actual UI. The `find` extension is included in CodeMirror's
+    // searchKeymap; dispatching a CustomEvent reaches any listening component.
+    'find.toggle': () => {
+      window.dispatchEvent(new CustomEvent('mc:find-toggle'));
+    },
+
+    // Sidebar panel switching — sidebar currently shows Files / Outline / Git
+    // in a single panel; selecting a section scrolls that section into view.
+    'view.sidebarPanel': (panel?: string) => {
+      if (!panel) return;
+      // Make sure the sidebar is visible so the user actually sees the switch.
+      if (!useAppStore.getState().sidebarVisible) {
+        useAppStore.getState().toggleSidebar();
+      }
+      const target = document.querySelector(
+        `[data-testid="sidebar-jump-${panel}"]`,
+      ) as HTMLButtonElement | null;
+      target?.click();
+    },
+    'view.bottomPanel': () => {
+      const current = useSettingsStore.getState().replOpen;
+      useSettingsStore.getState().setSetting('replOpen', !current);
+    },
+
+    'font.size': (direction?: string) => {
+      // Three settings: editorFontSize in px. Range 10..28.
+      const settings = useSettingsStore.getState();
+      const cur = settings.editorFontSize ?? 14;
+      const next =
+        direction === 'increase' ? Math.min(28, cur + 1) : direction === 'decrease' ? Math.max(10, cur - 1) : 14;
+      settings.setSetting('editorFontSize', next);
+    },
+
+    'theme.loadCustomCss': async () => {
+      const r = await ipc.file.pickFile();
+      if (!r.ok || !r.data) return;
+      useSettingsStore.getState().setSetting('customCssPath', r.data);
+      toast.success('Custom CSS loaded');
+    },
+    'theme.clearCustomCss': () => {
+      useSettingsStore.getState().setSetting('customCssPath', null);
+      toast.success('Custom CSS cleared');
+    },
+
+    'template.load': (name?: string) => {
+      if (!name) return;
+      const templates: Record<string, string> = {
+        'blog-post.md': '# Blog Post\n\n_Author • Date_\n\n## Introduction\n\n## Body\n\n## Conclusion\n',
+        'meeting-notes.md': '# Meeting Notes\n\n**Date:** \n**Attendees:** \n\n## Agenda\n\n## Discussion\n\n## Action items\n',
+        'technical-spec.md': '# Technical Specification\n\n## Overview\n\n## Goals\n\n## Design\n\n## Implementation\n\n## Testing\n',
+        'changelog.md': '# Changelog\n\n## [Unreleased]\n\n### Added\n- \n\n### Changed\n- \n\n### Fixed\n- \n',
+        'readme.md': '# Project\n\n## Description\n\n## Installation\n\n## Usage\n\n## License\n',
+        'project-plan.md': '# Project Plan\n\n## Goals\n\n## Milestones\n\n## Risks\n\n## Status\n',
+        'api-docs.md': '# API Documentation\n\n## Authentication\n\n## Endpoints\n\n### `GET /resource`\n\n### `POST /resource`\n',
+        'tutorial.md': '# Tutorial\n\n## Prerequisites\n\n## Step 1\n\n## Step 2\n\n## Conclusion\n',
+        'release-notes.md': '# Release Notes\n\n## New features\n\n## Improvements\n\n## Bug fixes\n',
+        'comparison.md': '# Comparison\n\n| Option | A | B |\n|---|---|---|\n| Cost |  |  |\n| Speed |  |  |\n',
+      };
+      const snippet = templates[name];
+      if (!snippet) {
+        toast.error(`Unknown template: ${name}`);
+        return;
+      }
+      insertSnippet(snippet);
+    },
+
+    'print.preview': () => {
+      window.dispatchEvent(new CustomEvent('mc:print-preview'));
+    },
+    'print.previewStyled': () => {
+      window.dispatchEvent(new CustomEvent('mc:print-preview-styled'));
+    },
+
+    'file.clearRecent': () => {
+      useFileStore.setState({ openTabs: [] });
+    },
+
+    // File → New — creates an unsaved buffer with a default name.
+    'file.new': () => {
+      const id = `untitled-${Date.now()}`;
+      const path = id;
+      useEditorStore.getState().openBuffer(id, path, '');
+      useFileStore.setState((s) => {
+        s.openTabs.push({ id, path, title: 'Untitled', dirty: true });
+        s.activeTabId = id;
+      });
+    },
+
+    // Navigate to heading — used by sidebar Outline click and Breadcrumb.
+    'editor.gotoHeading': (line?: number) => {
+      if (typeof line === 'number') scrollToLine(line);
+    },
+
+    // Outline click handler — extract the line from the current active buffer
+    // for the clicked heading and scroll to it.
+    'outline.goto': (headingText?: string) => {
+      if (!headingText) return;
+      const activeId = useFileStore.getState().activeTabId;
+      if (!activeId) return;
+      const buffer = useEditorStore.getState().buffers.get(activeId);
+      if (!buffer) return;
+      const headings: HeadingItem[] = extractHeadings(buffer.content);
+      const match = headings.find((h) => h.text === headingText);
+      if (match) scrollToLine(match.line);
+    },
   });
 
   const { register } = useCommandStore.getState();
@@ -82,7 +271,7 @@ export function registerMenuCommands(): void {
   });
   register('file.closeTab', () => {
     const { activeTabId, closeTab } = useFileStore.getState();
-    if (activeTabId) closeTab(activeTabId);
+    if (activeTabId) confirmCloseFlow(closeTab)(activeTabId);
   });
   register('tab.next', () => {
     const { openTabs, activeTabId, setActiveTab } = useFileStore.getState();
@@ -109,7 +298,6 @@ export function registerMenuCommands(): void {
 }
 
 export function useRegisterMenuCommands(): void {
-  // Register handlers in the command store.
   useEffect(() => {
     registerMenuCommands();
   }, []);
@@ -135,4 +323,5 @@ export function useBridgeNativeMenu(): void {
   useMenuAction('print-preview-styled', 'print.previewStyled');
   useMenuAction('file-opened', 'file.opened', (payload) => payload);
   useMenuAction('clear-recent-files', 'file.clearRecent');
+  useMenuAction('file-new', 'file.new');
 }