Add full-text search with Chinese tokenization using Pagefind

Integrated Pagefind for static site search with built-in Chinese word segmentation support.

Changes:
1. **Installed Pagefind** (v1.4.0) as dev dependency
2. **Updated build script** to run Pagefind indexing after Next.js build
   - Indexes all 69 pages with 5,711 words
   - Automatic Chinese (zh-tw) language detection
3. **Created search modal component** (components/search-modal.tsx)
   - Dynamic Pagefind UI loading (lazy-loaded on demand)
   - Keyboard shortcuts (Cmd+K / Ctrl+K)
   - Chinese translations for UI elements
   - Dark mode compatible styling
4. **Added search button to header** (components/site-header.tsx)
   - Integrated SearchButton with keyboard shortcut display
   - Modal state management
5. **Custom Pagefind styles** (styles/globals.css)
   - Tailwind-based styling to match site design
   - Dark mode support
   - Highlight styling for search results

Features:
- ✅ Full-text search across all blog posts and pages
- ✅ Built-in Chinese word segmentation (Unicode-based)
- ✅ Mixed Chinese/English query support
- ✅ Zero bundle impact (20KB lazy-loaded on search activation)
- ✅ Keyboard shortcuts (⌘K / Ctrl+K)
- ✅ Search result highlighting with excerpts
- ✅ Dark mode compatible

Technical Details:
- Pagefind runs post-build to index .next directory
- Search index stored in .next/pagefind/
- Chinese segmentation works automatically via Unicode boundaries
- No third-party services or API keys required

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

package.json

@@ -6,7 +6,7 @@
   "scripts": {
     "dev": "concurrently \"contentlayer2 dev\" \"next dev\"",
     "sync-assets": "node scripts/sync-assets.mjs",
-    "build": "npm run sync-assets && contentlayer2 build && next build",
+    "build": "npm run sync-assets && contentlayer2 build && next build && npx pagefind --site .next",
     "start": "next start",
     "lint": "next lint",
     "contentlayer": "contentlayer build"
@@ -45,8 +45,9 @@
     "concurrently": "^9.2.1",
     "eslint": "^9.39.1",
     "eslint-config-next": "^16.0.3",
+    "pagefind": "^1.4.0",
     "postcss": "^8.5.6",
     "tailwindcss": "^3.4.18",
     "typescript": "^5.9.3"
   }
-}
+}