fix: wire orphaned IPC channels, fix data-loss bug, print preview events, sidebar navigation

- Fix file.clearRecent sending IPC to main process instead of clearing openTabs
- Wire show-batch-converter, show-document-compare, open-header-footer-dialog IPC channels
- Add print preview event listeners (mc:print-preview, mc:print-preview-styled) in App.tsx
- Fix sidebar hidden bridge buttons toggling sidebar closed after scroll
- Update sidebar menu labels to match actual sections (Files, Outline, Git)
- Fix ipc.print to be an object with show/doPrint methods (was bare function)
- Update callers: ExportPdfDialog, pdf-export, PrintPreview
- Add 7 regression tests for all fixes
- Clean 2 obsolete snapshots
- Build Linux packages (deb, AppImage, snap) — 549 tests passing

tests/unit/App.test.tsx

@@ -0,0 +1,67 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { render, act, screen, fireEvent } from '@testing-library/react';
+import App from '@/App';
+import { useCommandStore } from '@/stores/command-store';
+import { useAppStore } from '@/stores/app-store';
+import { useFileStore } from '@/stores/file-store';
+import { useSettingsStore } from '@/stores/settings-store';
+import { useEditorStore } from '@/stores/editor-store';
+
+vi.mock('@/lib/ipc', () => ({
+  ipc: {
+    file: {
+      pickFolder: vi.fn(),
+      pickFile: vi.fn(),
+      read: vi.fn(),
+      write: vi.fn(),
+      list: vi.fn(),
+    },
+    app: { getVersion: vi.fn().mockResolvedValue({ ok: true, data: '5.0.1' }) },
+    menu: { on: vi.fn(() => () => {}) },
+    updater: { check: vi.fn(), install: vi.fn(), getState: vi.fn(), onStatus: vi.fn(() => () => {}) },
+    crash: { read: vi.fn(), openDir: vi.fn(), delete: vi.fn() },
+  },
+}));
+
+vi.mock('@/hooks/use-welcome-trigger', () => ({
+  useWelcomeTrigger: () => {},
+}));
+
+vi.mock('@/hooks/useAutoUpdateCheck', () => ({
+  useAutoUpdateCheck: () => {},
+}));
+
+describe('App — print preview event listeners', () => {
+  beforeEach(() => {
+    useCommandStore.setState({ handlers: {} } as any);
+    useAppStore.setState({ modal: { kind: null } } as any);
+    useFileStore.setState({ tree: null, rootPath: null, expanded: new Set(), openTabs: [], activeTabId: null });
+    useSettingsStore.getState().resetToDefaults?.();
+    useEditorStore.setState({ buffers: new Map(), activeId: null });
+    localStorage.clear();
+  });
+
+  it('opens PrintPreview on mc:print event', () => {
+    render(<App />);
+    act(() => {
+      window.dispatchEvent(new CustomEvent('mc:print'));
+    });
+    expect(screen.getByText(/print preview/i)).toBeInTheDocument();
+  });
+
+  it('opens PrintPreview on mc:print-preview event', () => {
+    render(<App />);
+    act(() => {
+      window.dispatchEvent(new CustomEvent('mc:print-preview'));
+    });
+    expect(screen.getByText(/print preview/i)).toBeInTheDocument();
+  });
+
+  it('opens PrintPreview on mc:print-preview-styled event', () => {
+    render(<App />);
+    act(() => {
+      window.dispatchEvent(new CustomEvent('mc:print-preview-styled'));
+    });
+    expect(screen.getByText(/print preview/i)).toBeInTheDocument();
+  });
+});