feat(docker): add nginx frontend image and full-stack compose

Build static assets with Vite, proxy /api to backend, and document server env vars.

Co-authored-by: Cursor <cursoragent@cursor.com>

docker-compose.yml

@@ -0,0 +1,58 @@
+services:
+  backend:
+    build:
+      context: ../backend-nest
+      dockerfile: Dockerfile
+    image: child-gold-land-backend:latest
+    container_name: child-gold-land-backend
+    env_file:
+      - .env.docker
+    environment:
+      NODE_ENV: production
+      PORT: 3000
+      HOST: 0.0.0.0
+      DB_PATH: /app/data/app.db
+      JWT_SECRET: ${JWT_SECRET}
+      CORS_ORIGIN: ${CORS_ORIGIN}
+    volumes:
+      - backend_sqlite:/app/data
+    restart: unless-stopped
+    healthcheck:
+      test:
+        [
+          "CMD",
+          "node",
+          "-e",
+          "fetch('http://127.0.0.1:3000/health').then(r=>process.exit(r.ok?0:1)).catch(()=>process.exit(1))",
+        ]
+      interval: 30s
+      timeout: 5s
+      retries: 3
+      start_period: 20s
+    networks:
+      - child-gold-land
+
+  frontend:
+    build:
+      context: .
+      dockerfile: Dockerfile
+      args:
+        VITE_API_URL: ${VITE_API_URL:-/api}
+    image: child-gold-land-frontend:latest
+    container_name: child-gold-land-frontend
+    ports:
+      - "${FRONTEND_PORT:-8080}:80"
+    depends_on:
+      backend:
+        condition: service_healthy
+    restart: unless-stopped
+    networks:
+      - child-gold-land
+
+volumes:
+  backend_sqlite:
+    name: child-gold-land-sqlite
+
+networks:
+  child-gold-land:
+    name: child-gold-land