Implement authentication and chat functionality with JWT support

- Added `auth.py` for mock login and JWT issuance.
- Introduced `chat.py` for handling chat requests with role-based access control.
- Enhanced `main.py` to include new routers and middleware for tracing.
- Implemented input validation in `input_guard.py` to prevent SQL injection.
- Created repositories for managing agent sessions and audit logs.
- Added exception handling for authorization errors.
- Updated settings to include JWT configuration.
- Introduced tests for authentication and input validation.

app/api/auth.py

@@ -0,0 +1,25 @@
+"""开发期 Mock 登录：签发 JWT。"""
+
+from __future__ import annotations
+
+from fastapi import APIRouter, Request
+
+from app.gateway.jwt_service import infer_roles, issue_token
+from app.model.schemas import LoginRequest, LoginResponseData
+from app.utils.response import ok
+
+router = APIRouter(prefix="/api/auth", tags=["auth"])
+
+
+@router.post("/login")
+def login(body: LoginRequest, request: Request):
+    roles = infer_roles(body.actor_id, body.token_type, body.roles)
+    token, expires_in = issue_token(body.actor_id, body.token_type, roles)
+    trace_id = getattr(request.state, "trace_id", "unknown")
+    data = LoginResponseData(
+        access_token=token,
+        expires_in=expires_in,
+        sub=body.actor_id,
+        roles=roles,
+    )
+    return ok(data.model_dump(), trace_id, message="login ok")