fix: SEO canonical URLs, LCP performance, remove unused dependencies

- Remove duplicate app/projects/ route (was causing 5xx and soft 404)
- Fix nginx: redirect www.dk0.dev → dk0.dev (non-www canonical)
- Fix not-found.tsx: locale-prefixed links, remove framer-motion dependency
- Add fetchPriority='high' and will-change to Hero LCP image
- Add preconnect hints for hardcover.app and cms.dk0.dev
- Reduce background blur from 100px to 80px (LCP rendering delay)
- Remove boneyard-js (~20 KiB), replace with custom Skeleton component
- Remove react-icons (~10 KiB), replace with inline SVGs
- Conditionally render mobile menu (saves ~20 DOM nodes)
- Add /books to sitemap
- Optimize image config with explicit deviceSizes/imageSizes

next.config.ts

@@ -33,7 +33,7 @@ const nextConfig: NextConfig = {
   // Performance optimizations
   experimental: {
     // Tree-shake barrel-file packages in both dev and production
-    optimizePackageImports: ["lucide-react", "framer-motion", "react-icons", "@tiptap/react"],
+    optimizePackageImports: ["lucide-react", "framer-motion", "@tiptap/react"],
     // Merge all CSS into a single chunk to eliminate the render-blocking CSS chain
     // (84dc7384.css → 3aefc04b.css sequential dependency reported by PageSpeed).
     cssChunking: false,
@@ -47,6 +47,8 @@ const nextConfig: NextConfig = {
   images: {
     formats: ["image/webp", "image/avif"],
     minimumCacheTTL: 2592000,
+    deviceSizes: [640, 768, 1024, 1280, 1536],
+    imageSizes: [16, 32, 48, 64, 96, 128, 256],
     remotePatterns: [
       {
         protocol: "https",
@@ -81,6 +83,11 @@ const nextConfig: NextConfig = {
 
   // Webpack configuration
   webpack: (config, { dev, isServer, webpack }) => {
+    // Skip adding polyfill webpack aliases — Next.js injects polyfills via <script>
+    // tags, not through webpack module resolution, so aliases don't take effect.
+    // The browserslist targets (chrome >= 100, etc.) already prevent unnecessary
+    // transpilation; the 11.7 KiB polyfill chunk is a known Next.js limitation.
+
     // Fix for module resolution issues
     config.resolve.fallback = {
       ...config.resolve.fallback,