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/app/globals.css

@@ -0,0 +1,94 @@
+@tailwind base;
+@tailwind components;
+@tailwind utilities;
+
+:root {
+  --font-inter: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
+
+  /* Colors */
+  --background: 24 24 27;
+  --foreground: 250 250 250;
+  --card: 39 39 42;
+  --card-foreground: 250 250 250;
+  --primary: 59 130 246;
+  --primary-foreground: 255 255 255;
+  --secondary: 63 63 70;
+  --secondary-foreground: 250 250 250;
+  --muted: 63 63 70;
+  --muted-foreground: 161 161 170;
+  --accent: 63 63 70;
+  --accent-foreground: 250 250 250;
+  --destructive: 239 68 68;
+  --destructive-foreground: 250 250 250;
+  --border: 63 63 70;
+  --input: 63 63 70;
+  --ring: 59 130 246;
+}
+
+* {
+  box-sizing: border-box;
+  padding: 0;
+  margin: 0;
+}
+
+html {
+  scroll-behavior: smooth;
+}
+
+body {
+  font-family: var(--font-inter);
+  background-color: rgb(var(--background));
+  color: rgb(var(--foreground));
+  min-height: 100vh;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+/* Custom scrollbar */
+::-webkit-scrollbar {
+  width: 8px;
+}
+
+::-webkit-scrollbar-track {
+  background: rgb(var(--background));
+}
+
+::-webkit-scrollbar-thumb {
+  background: rgb(var(--secondary));
+  border-radius: 4px;
+}
+
+::-webkit-scrollbar-thumb:hover {
+  background: rgb(var(--muted-foreground));
+}
+
+/* Selection */
+::selection {
+  background-color: rgb(var(--primary) / 0.3);
+}
+
+/* Focus styles */
+:focus-visible {
+  outline: 2px solid rgb(var(--ring));
+  outline-offset: 2px;
+}
+
+/* Smooth transitions */
+a,
+button {
+  transition: color 0.2s ease, background-color 0.2s ease, border-color 0.2s ease;
+}
+
+/* Utility classes */
+.text-gradient {
+  background: linear-gradient(135deg, rgb(var(--primary)) 0%, #8b5cf6 100%);
+  -webkit-background-clip: text;
+  -webkit-text-fill-color: transparent;
+  background-clip: text;
+}
+
+.glass {
+  background: rgb(var(--card) / 0.8);
+  backdrop-filter: blur(12px);
+  border: 1px solid rgb(var(--border) / 0.5);
+}