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

package.json

@@ -64,7 +64,6 @@
     "@tiptap/react": "^3.15.3",
     "@tiptap/starter-kit": "^3.15.3",
     "@vercel/og": "^0.6.5",
-    "boneyard-js": "^1.7.6",
     "clsx": "^2.1.1",
     "dotenv": "^16.6.1",
     "framer-motion": "^12.24.10",
@@ -76,7 +75,6 @@
     "nodemailer": "^7.0.11",
     "react": "^19.2.3",
     "react-dom": "^19.2.3",
-    "react-icons": "^5.5.0",
     "react-markdown": "^10.1.0",
     "redis": "^5.8.2",
     "sanitize-html": "^2.17.0",