feat: add models for physical files, policies, and user management

- Implement PhysicalFile model to manage physical file references and reference counting.
- Create Policy model with associated options and group links for storage policies.
- Introduce Redeem and Report models for handling redeem codes and reports.
- Add Settings model for site configuration and user settings management.
- Develop Share model for sharing objects with unique codes and associated metadata.
- Implement SourceLink model for managing download links associated with objects.
- Create StoragePack model for managing user storage packages.
- Add Tag model for user-defined tags with manual and automatic types.
- Implement Task model for managing background tasks with status tracking.
- Develop User model with comprehensive user management features including authentication.
- Introduce UserAuthn model for managing WebAuthn credentials.
- Create WebDAV model for managing WebDAV accounts associated with users.

sqlmodels/database_connection.py

@@ -0,0 +1,78 @@
+from typing import AsyncGenerator, ClassVar
+
+from loguru import logger
+from sqlalchemy import NullPool, AsyncAdaptedQueuePool
+from sqlalchemy.ext.asyncio import create_async_engine, AsyncEngine
+from sqlalchemy.orm import sessionmaker
+from sqlmodel import SQLModel
+from sqlmodel.ext.asyncio.session import AsyncSession
+
+
+class DatabaseManager:
+    engine: ClassVar[AsyncEngine | None] = None
+    _async_session_factory: ClassVar[sessionmaker | None] = None
+
+    @classmethod
+    async def get_session(cls) -> AsyncGenerator[AsyncSession]:
+        assert cls._async_session_factory is not None, "数据库引擎未初始化，请先调用 DatabaseManager.init()"
+        async with cls._async_session_factory() as session:
+            yield session
+
+    @classmethod
+    async def init(
+            cls,
+            database_url: str,
+            debug: bool = False,
+    ):
+        """
+        初始化数据库连接引擎。
+
+        :param database_url: 数据库连接URL
+        :param debug: 是否开启调试模式
+        """
+        # 构建引擎参数
+        engine_kwargs: dict = {
+            'echo': debug,
+            'future': True,
+        }
+
+        if debug:
+            # Debug 模式使用 NullPool（无连接池，每次创建新连接）
+            engine_kwargs['poolclass'] = NullPool
+        else:
+            # 生产模式使用 AsyncAdaptedQueuePool 连接池
+            engine_kwargs.update({
+                'poolclass': AsyncAdaptedQueuePool,
+                'pool_size': 40,
+                'max_overflow': 80,
+                'pool_timeout': 30,
+                'pool_recycle': 1800,
+                'pool_pre_ping': True,
+            })
+
+        # 只在需要时添加 connect_args
+        if database_url.startswith("sqlite"):
+            engine_kwargs['connect_args'] = {'check_same_thread': False}
+
+        cls.engine = create_async_engine(database_url, **engine_kwargs)
+
+        cls._async_session_factory = sessionmaker(cls.engine, class_=AsyncSession)
+
+        # 开发阶段直接 create_all 创建表结构
+        async with cls.engine.begin() as conn:
+            await conn.run_sync(SQLModel.metadata.create_all)
+
+        logger.info("数据库引擎初始化完成")
+
+    @classmethod
+    async def close(cls):
+        """
+        优雅地关闭数据库连接引擎。
+        仅应在应用结束时调用。
+        """
+        if cls.engine:
+            logger.info("正在关闭数据库连接引擎...")
+            await cls.engine.dispose()
+            logger.info("数据库连接引擎已成功关闭。")
+        else:
+            logger.info("数据库连接引擎未初始化，无需关闭。")