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

app/components/HeaderClient.tsx

@@ -1,12 +1,18 @@
 "use client";
 
 import { useState, useEffect, useRef } from "react";
-import { SiGithub, SiLinkedin } from "react-icons/si";
 import Link from "next/link";
 import { usePathname, useSearchParams } from "next/navigation";
 import type { NavTranslations } from "@/types/translations";
 import { ThemeToggle } from "./ThemeToggle";
 
+const SiGithubIcon = ({ size = 20 }: { size?: number }) => (
+  <svg xmlns="http://www.w3.org/2000/svg" width={size} height={size} viewBox="0 0 24 24" fill="currentColor"><path d="M12 0c-6.626 0-12 5.373-12 12 0 5.302 3.438 9.8 8.207 11.387.599.111.793-.261.793-.577v-2.234c-3.338.726-4.033-1.416-4.033-1.416-.546-1.387-1.333-1.756-1.333-1.756-1.089-.745.083-.729.083-.729 1.205.084 1.839 1.237 1.839 1.237 1.07 1.834 2.807 1.304 3.492.997.107-.775.418-1.305.762-1.604-2.665-.305-5.467-1.334-5.467-5.931 0-1.311.469-2.381 1.236-3.221-.124-.303-.535-1.524.117-3.176 0 0 1.008-.322 3.301 1.23.957-.266 1.983-.399 3.003-.404 1.02.005 2.047.138 3.006.404 2.291-1.552 3.297-1.23 3.297-1.23.653 1.653.242 2.874.118 3.176.77.84 1.235 1.911 1.235 3.221 0 4.609-2.807 5.624-5.479 5.921.43.372.823 1.102.823 2.222v3.293c0 .319.192.694.801.576 4.765-1.589 8.199-6.086 8.199-11.386 0-6.627-5.373-12-12-12z"/></svg>
+);
+const SiLinkedinIcon = ({ size = 20 }: { size?: number }) => (
+  <svg xmlns="http://www.w3.org/2000/svg" width={size} height={size} viewBox="0 0 24 24" fill="currentColor"><path d="M20.447 20.452h-3.554v-5.569c0-1.328-.027-3.037-1.852-3.037-1.853 0-2.136 1.445-2.136 2.939v5.667H9.351V9h3.414v1.561h.046c.477-.9 1.637-1.85 3.37-1.85 3.601 0 4.267 2.37 4.267 5.455v6.286zM5.337 7.433c-1.144 0-2.063-.926-2.063-2.065 0-1.138.92-2.063 2.063-2.063 1.14 0 2.064.925 2.064 2.063 0 1.139-.925 2.065-2.064 2.065zm1.782 13.019H3.555V9h3.564v11.452zM22.225 0H1.771C.792 0 0 .774 0 1.729v20.542C0 23.227.792 24 1.771 24h20.451C23.2 24 24 23.227 24 22.271V1.729C24 .774 23.2 0 22.222 0h.003z"/></svg>
+);
+
 // Inline SVG icons to avoid loading the full lucide-react chunk (~116KB)
 const MenuIcon = ({ size = 24 }: { size?: number }) => (
   <svg xmlns="http://www.w3.org/2000/svg" width={size} height={size} viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round"><line x1="4" x2="20" y1="12" y2="12"/><line x1="4" x2="20" y1="6" y2="6"/><line x1="4" x2="20" y1="18" y2="18"/></svg>
@@ -56,9 +62,9 @@ export default function HeaderClient({ locale, translations }: HeaderClientProps
   ];
 
   const socialLinks = [
-    { icon: SiGithub, href: "https://github.com/Denshooter", label: "GitHub" },
+    { icon: SiGithubIcon, href: "https://github.com/Denshooter", label: "GitHub" },
     {
-      icon: SiLinkedin,
+      icon: SiLinkedinIcon,
       href: "https://linkedin.com/in/dkonkol",
       label: "LinkedIn",
     },
@@ -145,19 +151,18 @@ export default function HeaderClient({ locale, translations }: HeaderClientProps
       </header>
 
       {/* Mobile menu overlay */}
-      <div
-        className={`fixed inset-0 bg-stone-900/50 backdrop-blur-sm z-40 md:hidden transition-opacity duration-200 ${
-          isOpen ? "opacity-100" : "opacity-0 pointer-events-none"
-        }`}
-        onClick={() => setIsOpen(false)}
-      />
+      {isOpen && (
+        <div
+          className="fixed inset-0 bg-stone-900/50 backdrop-blur-sm z-40 md:hidden"
+          onClick={() => setIsOpen(false)}
+        />
+      )}
 
       {/* Mobile menu panel */}
-      <div
-        className={`fixed right-0 top-0 h-full w-80 bg-white shadow-2xl z-50 md:hidden overflow-y-auto transition-transform duration-300 ease-out ${
-          isOpen ? "translate-x-0" : "translate-x-full"
-        }`}
-      >
+      {isOpen && (
+        <div
+          className="fixed right-0 top-0 h-full w-80 bg-white shadow-2xl z-50 md:hidden overflow-y-auto"
+        >
         <div className="p-6">
           <div className="flex justify-between items-center mb-8">
             <Link
@@ -236,7 +241,8 @@ export default function HeaderClient({ locale, translations }: HeaderClientProps
             </div>
           </div>
         </div>
-      </div>
+        </div>
+      )}
     </>
   );
 }