Complete Next.js migration with SSR and Docker deployment

- Migrate from vanilla JavaScript SPA to Next.js 16 with App Router
- Add server-side rendering for all pages (Home, Compare, Rankings)
- Create individual school pages with dynamic routing (/school/[urn])
- Implement Chart.js and Leaflet map integrations
- Add comprehensive SEO with sitemap, robots.txt, and JSON-LD
- Set up Docker multi-service architecture (PostgreSQL, FastAPI, Next.js)
- Update CI/CD pipeline to build both backend and frontend images
- Fix Dockerfile to include devDependencies for TypeScript compilation
- Add Jest testing configuration
- Implement performance optimizations (code splitting, caching)

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

nextjs-app/.env.example

@@ -0,0 +1,8 @@
+# API Configuration
+NEXT_PUBLIC_API_URL=http://localhost:8000/api
+
+# Production API URL (for deployment)
+# NEXT_PUBLIC_API_URL=https://api.schoolcompare.co.uk/api
+
+# Node Environment
+NODE_ENV=development