feat: 添加PostgreSQL支持并更新数据库配置

- 新增PostgreSQL服务支持，使用最新版17
- 更新Docker Compose配置以支持PostgreSQL和Redis
- 修改数据库连接逻辑，支持PostgreSQL和SQLite
- 更新文档以反映新的数据库配置和使用方法
- 优化数据模型，确保时间戳字段支持时区

api/docker-compose.yml

@@ -1,6 +1,32 @@
 version: '3.8'
 
 services:
+  # PostgreSQL 数据库（使用最新版 17）
+  postgres:
+    image: postgres:17-alpine
+    container_name: life-echo-postgres
+    ports:
+      - "5432:5432"
+    environment:
+      POSTGRES_USER: ${POSTGRES_USER:-postgres}
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-postgres}
+      POSTGRES_DB: ${POSTGRES_DB:-life_echo}
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    restart: always
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      interval: 10s
+      timeout: 5s
+      retries: 5
+    networks:
+      - life-echo-network
+    logging:
+      driver: "json-file"
+      options:
+        max-size: "10m"
+        max-file: "3"
+
   # Redis 服务（用于会话存储和 Celery 消息队列）
   redis:
     image: redis:7-alpine
@@ -36,11 +62,12 @@ services:
     env_file:
       - .env.prod
     environment:
+      - DATABASE_URL=postgresql://postgres:postgres@postgres:5432/life_echo
       - REDIS_URL=redis://redis:6379/0
-    volumes:
-      - ./life_echo.db:/app/life_echo.db
     restart: always
     depends_on:
+      postgres:
+        condition: service_healthy
       redis:
         condition: service_healthy
     healthcheck:
@@ -48,7 +75,7 @@ services:
       interval: 30s
       timeout: 10s
       retries: 3
-      start_period: 10s
+      start_period: 15s
     networks:
       - life-echo-network
     logging:
@@ -68,11 +95,12 @@ services:
     env_file:
       - .env.prod
     environment:
+      - DATABASE_URL=postgresql://postgres:postgres@postgres:5432/life_echo
       - REDIS_URL=redis://redis:6379/0
-    volumes:
-      - ./life_echo.db:/app/life_echo.db
     restart: always
     depends_on:
+      postgres:
+        condition: service_healthy
       redis:
         condition: service_healthy
       api:
@@ -96,9 +124,12 @@ services:
   #   env_file:
   #     - .env.prod
   #   environment:
+  #     - DATABASE_URL=postgresql://postgres:postgres@postgres:5432/life_echo
   #     - REDIS_URL=redis://redis:6379/0
   #   restart: always
   #   depends_on:
+  #     postgres:
+  #       condition: service_healthy
   #     redis:
   #       condition: service_healthy
   #   networks:
@@ -130,5 +161,7 @@ networks:
     driver: bridge
 
 volumes:
+  postgres_data:
+    driver: local
   redis_data:
     driver: local