fix: 修复环境报错问题

docker-compose.yml

@@ -22,12 +22,15 @@ services:
       context: ./backend
     container_name: exam-helper-backend
     restart: unless-stopped
+    # AI 相关变量优先从 .env.example 注入；若存在 .env 则覆盖同名项（见 Compose env_file 顺序）
+    env_file:
+      - .env.example
+      - path: .env
+        required: false
     environment:
       DATABASE_URL: postgresql+psycopg://exam_user:exam_pass@db:5432/exam_helper
-      CORS_ORIGINS: http://localhost:5173
-      QWEN_API_KEY: ${QWEN_API_KEY:-}
-      QWEN_BASE_URL: ${QWEN_BASE_URL:-https://dashscope.aliyuncs.com/compatible-mode/v1}
-      QWEN_MODEL: ${QWEN_MODEL:-qwen-plus}
+      # 本地开发 Vite + Docker 前端均需允许
+      CORS_ORIGINS: http://localhost:5173,http://localhost:8173
       UPLOAD_DIR: /app/uploads
     volumes:
       - uploads_data:/app/uploads
@@ -35,7 +38,7 @@ services:
       db:
         condition: service_healthy
     ports:
-      - "8866:8000"
+      - "127.0.0.1:8866:8000"
 
   frontend:
     build:
@@ -45,7 +48,7 @@ services:
     depends_on:
       - backend
     ports:
-      - "8173:80"
+      - "127.0.0.1:8173:80"
 
 volumes:
   postgres_data: