Migrate from Vite to Next.js 15 with SSR

- Replace Vite + React Router with Next.js 15 App Router
- Implement i18n with next-intl (URL-based: /de, /en, /sr)
- Add SSR/SSG for all pages (48 static pages generated)
- Setup Supabase SSR client for auth
- Migrate all pages: Home, About, Portfolio, Blog, Contact, Login, Dashboard, Imprint, Privacy, Terms
- Add Docker support with standalone output
- Replace i18next with next-intl JSON translations
- Use next/image for optimized images

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/components-vite/SkipToContent.tsx

@@ -0,0 +1,23 @@
+import React, { useState } from 'react';
+
+const SkipToContent: React.FC = () => {
+  const [isFocused, setIsFocused] = useState(false);
+
+  return (
+    <a
+      href="#main-content"
+      className={`
+        fixed top-4 left-4 px-4 py-2 bg-orange-500 text-white rounded-lg
+        transform transition-transform duration-200
+        ${isFocused ? 'translate-y-0' : '-translate-y-full'}
+        focus:outline-none focus:ring-2 focus:ring-orange-500 focus:ring-offset-2
+      `}
+      onFocus={() => setIsFocused(true)}
+      onBlur={() => setIsFocused(false)}
+    >
+      Skip to main content
+    </a>
+  );
+};
+
+export default SkipToContent