chore: initial commit — leaudit-platform project skeleton

17-table PostgreSQL schema with full Chinese column comments,
FastAPI project structure (admin/common/modules),
DSL rule files, and schema migration scripts.

fastapi_common/fastapi_common_sqlalchemy/database.py

@@ -0,0 +1,21 @@
+"""SQLAlchemy 异步引擎和 session 工厂。"""
+
+from __future__ import annotations
+
+from contextlib import asynccontextmanager
+
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+
+from fastapi_admin.config import ASYNCPG_DATABASE_URL
+
+_engine = create_async_engine(ASYNCPG_DATABASE_URL, echo=False, pool_size=20, max_overflow=10)
+
+_AsyncSessionFactory = async_sessionmaker(_engine, class_=AsyncSession, expire_on_commit=False)
+
+
+@asynccontextmanager
+async def GetAsyncSession():
+    """获取异步数据库 session（上下文管理器）。"""
+    async with _AsyncSessionFactory() as session:
+        yield session
+        await session.commit()