auto-claude: subtask-2-2 - Optimize next.config.ts for performance

next.config.ts

@@ -7,12 +7,20 @@ const withNextIntl = createNextIntlPlugin('./src/i18n/request.ts');
 const nextConfig: NextConfig = {
   output: 'standalone',
 
+  // Enable React strict mode for better error detection
+  reactStrictMode: true,
+
+  // Remove X-Powered-By header for security
+  poweredByHeader: false,
+
   pageExtensions: ['js', 'jsx', 'md', 'mdx', 'ts', 'tsx'],
 
   images: {
     formats: ['image/avif', 'image/webp'],
     deviceSizes: [640, 750, 828, 1080, 1200, 1920, 2048],
     imageSizes: [16, 32, 48, 64, 96, 128, 256, 384],
+    // Cache remote images for 30 days
+    minimumCacheTTL: 60 * 60 * 24 * 30,
     remotePatterns: [
       {
         protocol: 'https',
@@ -22,56 +30,80 @@ const nextConfig: NextConfig = {
   },
 
   experimental: {
-    optimizePackageImports: ['lucide-react', 'framer-motion'],
+    // Tree-shake large packages for smaller bundles
+    optimizePackageImports: [
+      'lucide-react',
+      'framer-motion',
+      '@supabase/supabase-js',
+      'clsx',
+      'tailwind-merge',
+      'react-intersection-observer',
+    ],
   },
 
   async headers() {
-    return [
+    // Security headers for all routes
+    const securityHeaders = [
       {
-        source: '/:path*',
-        headers: [
-          {
-            key: 'X-DNS-Prefetch-Control',
-            value: 'on',
-          },
-          {
-            key: 'X-Frame-Options',
-            value: 'SAMEORIGIN',
-          },
-          {
-            key: 'X-Content-Type-Options',
-            value: 'nosniff',
-          },
-        ],
+        key: 'X-DNS-Prefetch-Control',
+        value: 'on',
       },
+      {
+        key: 'X-Frame-Options',
+        value: 'SAMEORIGIN',
+      },
+      {
+        key: 'X-Content-Type-Options',
+        value: 'nosniff',
+      },
+      {
+        key: 'X-XSS-Protection',
+        value: '1; mode=block',
+      },
+      {
+        key: 'Referrer-Policy',
+        value: 'strict-origin-when-cross-origin',
+      },
+      {
+        // Enforce HTTPS (1 year, include subdomains, allow preload list)
+        key: 'Strict-Transport-Security',
+        value: 'max-age=31536000; includeSubDomains; preload',
+      },
+      {
+        // Restrict browser features for security
+        key: 'Permissions-Policy',
+        value: 'camera=(), microphone=(), geolocation=(), interest-cohort=()',
+      },
+    ];
+
+    // Long-term caching for immutable assets
+    const immutableCacheHeader = [
+      {
+        key: 'Cache-Control',
+        value: 'public, max-age=31536000, immutable',
+      },
+    ];
+
+    return [
+      // Apply security headers to all routes
+      {
+        source: '/:path*',
+        headers: securityHeaders,
+      },
+      // Cache static assets aggressively
       {
         source: '/fonts/:path*',
-        headers: [
-          {
-            key: 'Cache-Control',
-            value: 'public, max-age=31536000, immutable',
-          },
-        ],
+        headers: immutableCacheHeader,
       },
       {
         source: '/images/:path*',
-        headers: [
-          {
-            key: 'Cache-Control',
-            value: 'public, max-age=31536000, immutable',
-          },
-        ],
+        headers: immutableCacheHeader,
       },
       {
         source: '/_next/static/:path*',
-        headers: [
-          {
-            key: 'Cache-Control',
-            value: 'public, max-age=31536000, immutable',
-          },
-        ],
+        headers: immutableCacheHeader,
       },
-      // Content-Language Headers für jede Sprache (wichtig für Bing)
+      // Content-Language headers for SEO (important for Bing and other search engines)
       {
         source: '/de/:path*',
         headers: [
@@ -102,7 +134,7 @@ const nextConfig: NextConfig = {
     ];
   },
 
-  // Compiler-Optimierungen
+  // Compiler optimizations
   compiler: {
     removeConsole: process.env.NODE_ENV === 'production',
   },