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.

tests/test_wave0_input_guard.py

@@ -0,0 +1,16 @@
+"""Wave 0：输入防护测试。"""
+
+
+def test_block_sql_injection_in_chat(client):
+    login = client.post("/api/auth/login", json={"actor_id": "STAFF-20001", "token_type": "staff"})
+    token = login.json()["data"]["access_token"]
+    resp = client.post(
+        "/api/chat",
+        json={"message": "please DROP TABLE users"},
+        headers={
+            "Authorization": f"Bearer {token}",
+            "X-Agent-Type": "analyst",
+        },
+    )
+    assert resp.status_code == 400
+    assert resp.json()["code"] == 400