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/LazyComponent.tsx

@@ -0,0 +1,17 @@
+import React, { Suspense } from 'react';
+import LoadingSpinner from './LoadingSpinner';
+
+interface LazyComponentProps {
+  children: React.ReactNode;
+  fallback?: React.ReactNode;
+}
+
+const LazyComponent: React.FC<LazyComponentProps> = ({ children, fallback = <LoadingSpinner /> }) => {
+  return (
+      <Suspense fallback={fallback}>
+        {children}
+      </Suspense>
+  );
+};
+
+export default LazyComponent;