refactor: 统一配置文件系统

- 补全 backend/config.yaml 所有非敏感配置项并添加中文注释
- 重写 config.go：Load(workDir) 显式传参，BindEnv 绑定敏感字段，删除 AutomaticEnv
- setDefaults 默认值与 config.yaml 保持一致（mimo/dashscope）
- backend/.env.example 重写为纯敏感信息模板
- .env 固定在 /opt/camtalk/.env，docker-compose 通过绝对路径加载
- deploy.sh 统一使用 --env-file，移除硬编码 IP
- deploy.yml 删除 CI 写入 .env 的步骤
- Dockerfile 移除 COPY config.yaml
- 修复 deploy.yml 中 POSTGRES_PASSWORD 的 &{{ 拼写错误

docker-compose.yml

@@ -17,11 +17,11 @@ services:
       context: ./backend
       dockerfile: Dockerfile
     container_name: camtalk-backend
+    env_file:
+      - /opt/camtalk/.env
     environment:
-      - APP_ENV=production
-      - CAMTALK_STORAGE_DRIVER=postgres
-      - CAMTALK_STORAGE_DSN=postgres://camtalk:camtalk123@postgres:5432/camtalk?sslmode=disable
-      - CAMTALK_AUTH_JWT_SECRET=78uWBBAF8XEQEotKDlrnlnd4y8i4WN3E4zXmNmC8BYQ=
+      - CAMTALK_STORAGE_DRIVER=${CAMTALK_STORAGE_DRIVER:-postgres}
+      - CAMTALK_STORAGE_DSN=postgres://${POSTGRES_USER}:${POSTGRES_PASSWORD}@postgres:5432/camtalk?sslmode=disable
     depends_on:
       postgres:
         condition: service_healthy
@@ -30,12 +30,11 @@ services:
     restart: unless-stopped
 
   postgres:
-    # 轩辕镜像加速，避免 Docker Hub 拉取超时
     image: docker.m.daocloud.io/library/postgres:15-alpine
     container_name: camtalk-postgres
     environment:
-      POSTGRES_USER: camtalk
-      POSTGRES_PASSWORD: camtalk123
+      POSTGRES_USER: ${POSTGRES_USER}
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
       POSTGRES_DB: camtalk
     volumes:
       - pgdata:/var/lib/postgresql/data
@@ -43,7 +42,7 @@ services:
     networks:
       - camtalk-net
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U camtalk -d camtalk"]
+      test: ["CMD-SHELL", "pg_isready -U ${POSTGRES_USER} -d camtalk"]
       interval: 5s
       timeout: 3s
       retries: 10