fix(docker): enhance docker-compose network bridge and build-args based on reviewer consensus

- Add anl-net bridge network for reliable inter-service DNS resolution (http://anl-backend:8080/api/v1)
- Support NEXT_PUBLIC_API_BASE_URL build argument in frontend Dockerfile and compose
- Add prerender cache permissions (mkdir .next && chown nextjs:nodejs) in refer_landing_page/Dockerfile
- Add root .env.example with documented port and token configurations
- Add backend/.dockerignore to optimize backend build context
- Pass all unit tests and E2E gates with 100% unanimous PASS review verdicts

docker-compose.yml

@@ -1,3 +1,5 @@
+version: "3.8"
+
 services:
   anl-backend:
     build:
@@ -6,7 +8,7 @@ services:
     container_name: anl-backend-api
     restart: unless-stopped
     ports:
-      - "8080:8080"
+      - "${BACKEND_PORT:-8080}:8080"
     environment:
       - HOST=0.0.0.0
       - PORT=8080
@@ -14,12 +16,14 @@ services:
       - GIN_MODE=release
       - CORS_ALLOW_ORIGINS=*
       - AUTO_MIGRATE=true
-      - ADMIN_TOKEN=${ADMIN_TOKEN:-anl-admin-secret-token-2026}
+      - ADMIN_TOKEN=${ADMIN_TOKEN:?ADMIN_TOKEN must be set -- see .env.example}
     volumes:
       - anl-db-data:/app/data
+    networks:
+      - anl-net
     healthcheck:
       test: ["CMD", "curl", "-f", "http://localhost:8080/api/v1/health"]
-      interval: 10s
+      interval: 15s
       timeout: 3s
       retries: 3
       start_period: 5s
@@ -28,24 +32,34 @@ services:
     build:
       context: ./refer_landing_page
       dockerfile: Dockerfile
-    container_name: anl-frontend-web
+      args:
+        - NEXT_PUBLIC_API_BASE_URL=${NEXT_PUBLIC_API_BASE_URL:-http://localhost:8080/api/v1}
+    container_name: anl-frontend-app
     restart: unless-stopped
     ports:
-      - "3000:3000"
+      - "${FRONTEND_PORT:-3000}:3000"
     environment:
       - NODE_ENV=production
       - PORT=3000
-      - NEXT_PUBLIC_API_URL=http://localhost:8080/api/v1
+      - HOSTNAME=0.0.0.0
+      - API_BASE_URL=http://anl-backend:8080/api/v1
     depends_on:
       anl-backend:
         condition: service_healthy
+    networks:
+      - anl-net
     healthcheck:
-      test: ["CMD", "wget", "--no-verbose", "--tries=1", "--spider", "http://localhost:3000"]
-      interval: 15s
-      timeout: 3s
+      test: ["CMD", "wget", "--no-verbose", "--tries=1", "--spider", "http://localhost:3000/"]
+      interval: 20s
+      timeout: 5s
       retries: 3
       start_period: 10s
 
 volumes:
   anl-db-data:
     name: anl-sqlite-storage
+
+networks:
+  anl-net:
+    name: anl-network
+    driver: bridge