Add React frontend to Docker Compose

- Created frontend/Dockerfile with multi-stage build for optimized production bundle
- Created frontend/.dockerignore to exclude node_modules and build artifacts
- Added frontend service to docker-compose.yml with:
  - Auto-build from frontend/Dockerfile
  - Port 3000 mapping
  - Health checks (wget to http://localhost:3000)
  - Dependency on healthy Kafka and Redis
  - Production environment (NODE_ENV=production)
  - Auto-restart on failure
  - Proper network connectivity
- Created DOCKER_QUICK_START.md with simplified setup guide:
  - Single docker compose up starts infrastructure + frontend
  - Cleaner workflow (2-3 terminals instead of 4)
  - Production-like testing (not dev mode)
  - Complete troubleshooting section
- Updated FULLSTACK_GUIDE.md to highlight Docker-integrated frontend
- Frontend now runs as optimized 63KB gzip production build in Docker

All components now start together:
  docker compose up      # Infrastructure + React frontend (Docker)
  uvicorn api.main:app   # API (your terminal)
  python pipeline.py     # Consumer (your terminal)

Access frontend at: http://localhost:3000

Co-authored-by: Copilot <[email protected]>

docker-compose.yml

@@ -47,6 +47,28 @@ services:
     volumes:
       - redis_data:/data
 
+  frontend:
+    build:
+      context: ./frontend
+      dockerfile: Dockerfile
+    ports:
+      - "3000:3000"
+    networks:
+      - payguard-network
+    depends_on:
+      kafka:
+        condition: service_healthy
+      redis:
+        condition: service_healthy
+    healthcheck:
+      test: wget --quiet --tries=1 --spider http://localhost:3000 || exit 1
+      interval: 10s
+      timeout: 5s
+      retries: 5
+    environment:
+      - NODE_ENV=production
+    restart: unless-stopped
+
 volumes:
   redis_data: