```

feat: 添加公司AI管理平台基础架构

添加了完整的FastAPI后端项目结构，包括：
- 环境配置文件(.env.example)和项目说明文档(README.md、AGENTS.md)
- Dockerfile用于容器化部署
- 核心基础设施：配置管理、数据库连接、调度器、安全认证
- 模块化设计：AI代理、审批流程、审计日志、业务台账等功能模块
- 支持多数据库连接(主库和遗留系统只读库)
- AI适配器支持OpenClaw、Hermes、OpenAI兼容接口
- 飞书集成、报表生成、风险监控等企业级功能
- 完整的依赖管理和测试指南
```

app/core/database.py

@@ -0,0 +1,51 @@
+from collections.abc import Generator
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import DeclarativeBase, Session, sessionmaker
+
+from app.core.config import get_settings
+
+
+class Base(DeclarativeBase):
+    """Base class for SQLAlchemy ORM models."""
+
+    pass
+
+
+settings = get_settings()
+
+engine = create_engine(settings.database_url, pool_pre_ping=True, pool_recycle=3600)
+SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False, expire_on_commit=False)
+
+legacy_engine = (
+    create_engine(settings.legacy_database_url, pool_pre_ping=True, pool_recycle=3600)
+    if settings.legacy_database_url
+    else None
+)
+LegacySessionLocal = (
+    sessionmaker(bind=legacy_engine, autoflush=False, autocommit=False, expire_on_commit=False)
+    if legacy_engine
+    else None
+)
+
+
+def get_db() -> Generator[Session, None, None]:
+    """Yield an application database session for FastAPI dependencies."""
+
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+
+def get_legacy_db() -> Generator[Session, None, None]:
+    """Yield a legacy database session when the legacy connection is configured."""
+
+    if LegacySessionLocal is None:
+        raise RuntimeError("LEGACY_DATABASE_URL is not configured")
+    db = LegacySessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()