feat: AI虚拟用户新闻互动系统 v1.3.0 初始提交

- 虚拟用户管理（昵称/头像/性别/简介/邮箱同步到目标平台）
- AI互动调度（点赞/收藏/评论/转发）
- 日志时间改为北京时间
- 评论达上限后继续执行点赞收藏转发
- 一键登出全部功能
- 浅色主题UI

backend/app/core/database.py

@@ -0,0 +1,72 @@
+"""数据库连接管理"""
+import asyncio
+from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession, async_sessionmaker
+from sqlalchemy.orm import DeclarativeBase
+from app.core.config import settings
+from app.core.logger import logger
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+engine = create_async_engine(
+    settings.DATABASE_URL,
+    echo=False,
+    pool_pre_ping=True,
+    pool_recycle=3600,
+    pool_size=10,
+    max_overflow=20,
+)
+
+AsyncSessionLocal = async_sessionmaker(
+    engine, class_=AsyncSession, expire_on_commit=False
+)
+
+
+async def get_db():
+    """获取数据库会话"""
+    async with AsyncSessionLocal() as session:
+        try:
+            yield session
+            await session.commit()
+        except Exception:
+            await session.rollback()
+            raise
+        finally:
+            await session.close()
+
+
+async def wait_for_db(max_retries: int = 30, interval: int = 2):
+    """等待 MySQL 就绪，最多重试 max_retries 次"""
+    for attempt in range(1, max_retries + 1):
+        try:
+            async with engine.begin() as conn:
+                await conn.execute(__import__("sqlalchemy").text("SELECT 1"))
+            logger.info(f"✅ 数据库连接成功（第 {attempt} 次尝试）")
+            return
+        except Exception as e:
+            if attempt == max_retries:
+                logger.error(f"数据库连接失败，已重试 {max_retries} 次: {e}")
+                raise
+            logger.warning(f"数据库未就绪，{interval}s 后重试（{attempt}/{max_retries}）: {e}")
+            await asyncio.sleep(interval)
+
+
+async def init_db():
+    """初始化数据库 - 等待 MySQL 就绪并注册所有模型"""
+    try:
+        # 等待 MySQL 容器真正就绪
+        await wait_for_db(max_retries=30, interval=2)
+
+        # 导入所有模型类，确保 SQLAlchemy ORM 元数据注册
+        from app.models import (
+            VirtualUser, UserPersonality, InteractionRecord,
+            TokenStat, AIModelConfig, SystemConfig, LoginLog
+        )
+        logger.info("✅ 数据库模型注册成功")
+        logger.info("✅ 数据库初始化完成")
+
+    except Exception as e:
+        logger.error(f"数据库初始化失败: {e}")
+        raise