feat: add welcome tab, presentation/publishing exports, and spell checking

- Developer format support (JSON, YAML, XML, TOML) import/export
- Presentation export (Reveal.js slides, Beamer PDF)
- Publishing format exports (Confluence wiki, MOBI e-book)
- Enable system spell checking with context menu suggestions
- Add welcome tab with onboarding and feature showcase

src/index.html

@@ -10,6 +10,7 @@
     <link rel="stylesheet" href="styles-modern.css">
     <link rel="stylesheet" href="styles-concreteinfo.css">
     <link rel="stylesheet" href="styles-sidebar.css">
+    <link rel="stylesheet" href="styles-welcome.css">
     <!-- Load external resources asynchronously -->
     <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.9.0/styles/default.min.css" media="print" onload="this.media='all'">
     <script defer src="https://cdn.jsdelivr.net/npm/mermaid@10/dist/mermaid.min.js"></script>

src/renderer.js

@@ -18,6 +18,7 @@ const { renderSnippetsPanel } = require('./sidebar/snippets-panel');
 const { ReplPanel } = require('./repl/repl-panel');
 const { CommandPalette } = require('./command-palette');
 const { PrintPreview } = require('./print-preview');
+const { createWelcomeContent } = require('./welcome');
 
 // Configure marked with highlight extension
 marked.use(markedHighlight({
@@ -1192,6 +1193,52 @@ document.addEventListener('DOMContentLoaded', () => {
         })
     });
 
+    // Welcome tab on startup
+    const hasLaunched = localStorage.getItem('hasLaunchedBefore');
+    const showWelcome = localStorage.getItem('showWelcomeOnStartup') !== 'false';
+
+    if (!hasLaunched || showWelcome) {
+        localStorage.setItem('hasLaunchedBefore', 'true');
+
+        // Set welcome content in the first tab's preview
+        const recentFiles = JSON.parse(localStorage.getItem('recentFiles') || '[]');
+        const welcomeHtml = createWelcomeContent(recentFiles);
+
+        const tab = tabManager.tabs.get(tabManager.activeTabId);
+        if (tab) {
+            tab.title = 'Welcome';
+            tab.content = '';
+            const preview = document.getElementById(`preview-${tab.id}`);
+            if (preview) {
+                preview.innerHTML = welcomeHtml;
+                // Wire up card actions
+                preview.querySelectorAll('.welcome-card').forEach(card => {
+                    card.addEventListener('click', () => {
+                        const action = card.dataset.action;
+                        if (action === 'new-file') tabManager.createNewTab();
+                        else if (action === 'open-file') ipcRenderer.send('menu-open');
+                        else if (action === 'open-template') sidebarManager.togglePanel('templates');
+                        else if (action === 'command-palette') {
+                            if (typeof commandPalette !== 'undefined') commandPalette.open();
+                        }
+                    });
+                });
+                // Wire up recent files
+                preview.querySelectorAll('.welcome-recent-item').forEach(item => {
+                    item.addEventListener('click', () => ipcRenderer.send('open-file-path', item.dataset.path));
+                });
+                // Wire up show-on-startup checkbox
+                const checkbox = document.getElementById('show-welcome-startup');
+                if (checkbox) {
+                    checkbox.addEventListener('change', () => {
+                        localStorage.setItem('showWelcomeOnStartup', checkbox.checked);
+                    });
+                }
+            }
+            tabManager.updateTabBar();
+        }
+    }
+
     // Image paste handler
     document.addEventListener('paste', async (e) => {
         const items = e.clipboardData?.items;

src/styles-welcome.css

@@ -0,0 +1,24 @@
+.welcome-container { padding: 40px; max-width: 900px; margin: 0 auto; }
+.welcome-hero { text-align: center; margin-bottom: 40px; }
+.welcome-title { font-size: 32px; font-weight: 700; color: var(--gray-800, #1f2937); }
+.welcome-version { font-size: 14px; color: var(--primary-dark, #5661b3); margin-top: 4px; font-weight: 500; }
+.welcome-subtitle { font-size: 16px; color: var(--gray-500, #6b7280); margin-top: 8px; }
+.welcome-grid { display: grid; gap: 32px; }
+.welcome-section h2 { font-size: 18px; margin-bottom: 16px; color: var(--gray-700, #374151); }
+.welcome-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 12px; }
+.welcome-card { padding: 20px; border: 1px solid var(--gray-200, #e5e7eb); border-radius: 12px; cursor: pointer; text-align: center; transition: all 0.2s; }
+.welcome-card:hover { border-color: var(--primary-dark, #5661b3); box-shadow: 0 4px 12px rgba(0,0,0,0.08); transform: translateY(-2px); }
+.welcome-card-icon { font-size: 28px; margin-bottom: 8px; }
+.welcome-card h3 { font-size: 15px; margin-bottom: 4px; }
+.welcome-card p { font-size: 13px; color: var(--gray-500); }
+.welcome-card kbd { display: inline-block; margin-top: 8px; padding: 2px 8px; background: var(--gray-100); border: 1px solid var(--gray-300); border-radius: 4px; font-size: 12px; font-family: 'JetBrains Mono', monospace; }
+.welcome-features { list-style: none; padding: 0; }
+.welcome-features li { padding: 6px 0; font-size: 14px; border-bottom: 1px solid var(--gray-100, #f3f4f6); }
+.welcome-features strong { color: var(--primary-dark, #5661b3); }
+.welcome-recent-item { padding: 8px 12px; border-radius: 6px; cursor: pointer; margin-bottom: 4px; }
+.welcome-recent-item:hover { background: var(--gray-100); }
+.welcome-recent-name { font-size: 14px; font-weight: 500; display: block; }
+.welcome-recent-path { font-size: 12px; color: var(--gray-500); display: block; margin-top: 2px; overflow: hidden; text-overflow: ellipsis; }
+.welcome-muted { color: var(--gray-400); font-size: 14px; }
+.welcome-footer { margin-top: 32px; text-align: center; }
+.welcome-checkbox { font-size: 13px; color: var(--gray-500); cursor: pointer; }

src/welcome.js

@@ -0,0 +1,78 @@
+function createWelcomeContent(recentFiles = []) {
+    const recentHtml = recentFiles.length
+        ? recentFiles.map(f => {
+            const name = f.split(/[/\\]/).pop();
+            return `<div class="welcome-recent-item" data-path="${f}"><span class="welcome-recent-name">${name}</span><span class="welcome-recent-path">${f}</span></div>`;
+        }).join('')
+        : '<p class="welcome-muted">No recent files</p>';
+
+    return `
+    <div class="welcome-container">
+        <div class="welcome-hero">
+            <h1 class="welcome-title">MarkdownConverter</h1>
+            <p class="welcome-version">Version 4.0.0</p>
+            <p class="welcome-subtitle">Professional Markdown Editor & Universal Document Converter</p>
+        </div>
+
+        <div class="welcome-grid">
+            <div class="welcome-section">
+                <h2>Quick Start</h2>
+                <div class="welcome-cards">
+                    <div class="welcome-card" data-action="new-file">
+                        <div class="welcome-card-icon">+</div>
+                        <h3>New Document</h3>
+                        <p>Create a blank document</p>
+                        <kbd>Ctrl+N</kbd>
+                    </div>
+                    <div class="welcome-card" data-action="open-file">
+                        <div class="welcome-card-icon">&#128194;</div>
+                        <h3>Open File</h3>
+                        <p>Open an existing file</p>
+                        <kbd>Ctrl+O</kbd>
+                    </div>
+                    <div class="welcome-card" data-action="open-template">
+                        <div class="welcome-card-icon">&#128203;</div>
+                        <h3>From Template</h3>
+                        <p>Start from a template</p>
+                    </div>
+                    <div class="welcome-card" data-action="command-palette">
+                        <div class="welcome-card-icon">&#8984;</div>
+                        <h3>Command Palette</h3>
+                        <p>Search all actions</p>
+                        <kbd>Ctrl+Shift+P</kbd>
+                    </div>
+                </div>
+            </div>
+
+            <div class="welcome-section">
+                <h2>What's New in v4.0.0</h2>
+                <ul class="welcome-features">
+                    <li><strong>CodeMirror Editor</strong> — Syntax highlighting, code folding, multiple cursors</li>
+                    <li><strong>Sidebar Panels</strong> — File Explorer, Git, Snippets, Templates</li>
+                    <li><strong>Command Palette</strong> — Quick access to all actions</li>
+                    <li><strong>Code Execution</strong> — Run JS, Python, Bash from code blocks</li>
+                    <li><strong>Print Preview</strong> — Full print customization dialog</li>
+                    <li><strong>New Formats</strong> — Reveal.js, YAML, JSON, Confluence, and more</li>
+                    <li><strong>Spell Checking</strong> — System dictionary with suggestions</li>
+                    <li><strong>Markdown Extensions</strong> — Footnotes, admonitions, TOC</li>
+                    <li><strong>Image Handling</strong> — Paste and drag-drop images</li>
+                    <li><strong>PlantUML</strong> — Diagram rendering in preview</li>
+                </ul>
+            </div>
+
+            <div class="welcome-section">
+                <h2>Recent Files</h2>
+                <div class="welcome-recent">${recentHtml}</div>
+            </div>
+        </div>
+
+        <div class="welcome-footer">
+            <label class="welcome-checkbox">
+                <input type="checkbox" id="show-welcome-startup" checked>
+                Show this tab on startup
+            </label>
+        </div>
+    </div>`;
+}
+
+module.exports = { createWelcomeContent };