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>

.claude/settings.local.json

@@ -39,7 +39,18 @@
       "Bash(pip install:*)",
       "Bash(python:*)",
       "Bash(pyftsubset:*)",
-      "Bash(NODE_TLS_REJECT_UNAUTHORIZED=0 node:*)"
+      "Bash(NODE_TLS_REJECT_UNAUTHORIZED=0 node:*)",
+      "WebFetch(domain:pagespeed.web.dev)",
+      "Bash(npx tsx:*)",
+      "Bash(npx next build)",
+      "Bash(npx next:*)",
+      "Bash(npm --version:*)",
+      "Bash(npm i)",
+      "Bash(npm cache clean:*)",
+      "Bash(npm init -y)",
+      "Bash(npx create-next-app@latest:*)",
+      "Bash(echo \"npm install failed with exit code $?\")",
+      "Bash(echo:*)"
     ],
     "deny": []
   }