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/public/manifest.json

@@ -0,0 +1,16 @@
+{
+  "name": "SchoolCompare",
+  "short_name": "SchoolCompare",
+  "description": "Compare primary school KS2 performance across England",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#ffffff",
+  "theme_color": "#3b82f6",
+  "icons": [
+    {
+      "src": "/favicon.svg",
+      "sizes": "any",
+      "type": "image/svg+xml"
+    }
+  ]
+}