feat(arch): unify frontend and backend into single Go backend server with static export

- Configure Next.js static export (output: 'export') with client-side dynamic fetching
- Implement Go static serving with SPA fallback in backend/internal/router/router.go
- Unify multi-stage build in backend/Dockerfile (Node -> Go -> minimal Alpine runtime)
- Simplify root docker-compose.yml to single anl-app service on port 8080
- Update REQUIREMENTS.md DM-03 and AC-17 normative contracts to v3.0 Unified Go Backend
- Restore strict regression verification in Gate 9 (AC-35/36/37) and unittest suite
- All Go unit tests, TypeScript type checks, ESLint, and E2E gates passed clean

docker-compose.yml

@@ -1,14 +1,16 @@
 version: "3.8"
 
 services:
-  anl-backend:
+  anl-app:
     build:
-      context: ./backend
-      dockerfile: Dockerfile
-    container_name: anl-backend-api
+      context: .
+      dockerfile: backend/Dockerfile
+      args:
+        - NEXT_PUBLIC_API_BASE_URL=${NEXT_PUBLIC_API_BASE_URL:-}
+    container_name: anl-app
     restart: unless-stopped
     ports:
-      - "${BACKEND_PORT:-8080}:8080"
+      - "${APP_PORT:-8080}:8080"
     environment:
       - HOST=0.0.0.0
       - PORT=8080
@@ -19,8 +21,6 @@ services:
       - ADMIN_TOKEN=${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: 15s
@@ -28,38 +28,6 @@ services:
       retries: 3
       start_period: 5s
 
-  anl-frontend:
-    build:
-      context: ./refer_landing_page
-      dockerfile: Dockerfile
-      args:
-        - NEXT_PUBLIC_API_BASE_URL=${NEXT_PUBLIC_API_BASE_URL:-http://localhost:8080/api/v1}
-    container_name: anl-frontend-app
-    restart: unless-stopped
-    ports:
-      - "${FRONTEND_PORT:-3000}:3000"
-    environment:
-      - NODE_ENV=production
-      - PORT=3000
-      - 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: 20s
-      timeout: 5s
-      retries: 3
-      start_period: 10s
-
 volumes:
   anl-db-data:
     name: anl-sqlite-storage
-
-networks:
-  anl-net:
-    name: anl-network
-    driver: bridge