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>

scripts/build-frontend.js

@@ -0,0 +1,68 @@
+#!/usr/bin/env node
+
+const esbuild = require('esbuild');
+const path = require('path');
+const fs = require('fs');
+
+// Ensure output directory exists
+const outdir = path.join(__dirname, '..', 'public', 'dist');
+if (!fs.existsSync(outdir)) {
+  fs.mkdirSync(outdir, { recursive: true });
+}
+
+// Build configuration
+const buildOptions = {
+  entryPoints: [
+    // Main app bundles
+    'src/frontend/app-main.ts',
+    'src/frontend/app-admin.ts',
+    'src/frontend/app-privacy.ts',
+    
+    // Shared components will be imported by the above
+  ],
+  bundle: true,
+  outdir: outdir,
+  format: 'iife', // Immediately Invoked Function Expression for browsers
+  platform: 'browser',
+  target: ['es2020'], // Modern browsers, matching our TypeScript target
+  sourcemap: process.env.NODE_ENV !== 'production',
+  minify: process.env.NODE_ENV === 'production',
+  loader: {
+    '.ts': 'ts',
+  },
+  define: {
+    'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV || 'development')
+  },
+  // Don't bundle these - they'll be loaded from CDN
+  external: ['leaflet'],
+};
+
+// Build function
+async function build() {
+  const isWatch = process.argv.includes('--watch');
+  
+  try {
+    if (isWatch) {
+      // Watch mode for development
+      const ctx = await esbuild.context(buildOptions);
+      await ctx.watch();
+      console.log('👀 Watching for frontend changes...');
+    } else {
+      // One-time build
+      console.log('🔨 Building frontend...');
+      const result = await esbuild.build(buildOptions);
+      console.log('✅ Frontend build complete!');
+      
+      if (result.errors.length > 0) {
+        console.error('❌ Build errors:', result.errors);
+        process.exit(1);
+      }
+    }
+  } catch (error) {
+    console.error('❌ Build failed:', error);
+    process.exit(1);
+  }
+}
+
+// Run the build
+build();