Add TypeScript frontend build system with shared components

- Set up esbuild for fast TypeScript compilation of frontend code
- Create SharedHeader component with factories for main/admin/privacy pages
- Create SharedFooter component with standard and minimal variants
- Add frontend build scripts (build:frontend, watch:frontend, dev:full)
- Configure TypeScript for browser environment with DOM types
- Add example page demonstrating shared component usage
- Update .gitignore to exclude compiled frontend files

Benefits:
- Type-safe frontend components
- Consistent headers/footers across all pages
- Single source of truth for common UI elements
- Built-in i18n and theme toggle support

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

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

.gitignore

@@ -30,6 +30,7 @@ Thumbs.db
 # Generated files
 public/style.css
 public/style.css.map
+public/dist/
 
 # TypeScript build outputs
 dist/