refactor(api): TOML 配置 SSOT、统一错误契约、Auth/事务加固与可观测性 (#33)

配置 SSOT（TOML + .env）
统一错误契约
Auth 与事务边界
Redis / Celery 可靠性:业务 Redis（DB/0）与 Celery broker/backend（DB/1）显式拆分；连接池、sync client
可观测性（OpenTelemetry + LGTM）

api/tests/test_avatar_preset_http.py

@@ -18,6 +18,7 @@ from app.features.auth.deps import get_auth_service
 from app.features.auth.router import router as auth_router
 from app.features.auth.service import AuthService
 from app.features.user.models import User
+from tests.conftest import install_test_error_handlers
 
 
 def _mock_current_user() -> User:
@@ -35,7 +36,7 @@ def _mock_current_user() -> User:
 
 @pytest.fixture
 def preset_auth_app() -> FastAPI:
-    app = FastAPI()
+    app = install_test_error_handlers(FastAPI())
     app.include_router(auth_router)
 
     fixed_user = _mock_current_user()
@@ -197,10 +198,9 @@ async def test_upload_avatar_cos_calls_storage_and_presigns(
     uid = str(uuid.uuid4())
     public = f"https://{bucket}.cos.{region}.myqcloud.com/avatars/{uid}.jpg"
     for attr, val in (
-        ("tencent_cos_secret_id", "sid"),
-        ("tencent_cos_secret_key", "sk"),
+        ("tencent_secret_id", "sid"),
+        ("tencent_secret_key", "sk"),
         ("tencent_cos_bucket", bucket),
-        ("tencent_cos_region", region),
         ("tencent_cos_base_url", f"https://{bucket}.cos.{region}.myqcloud.com"),
     ):
         monkeypatch.setattr(settings, attr, val, raising=False)
@@ -214,19 +214,27 @@ async def test_upload_avatar_cos_calls_storage_and_presigns(
     fixed_user.id = uid
     fixed_user.avatar_url = None
 
-    async def _fake_update_avatar(u: str, url: str):
+    async def _fake_upload_avatar(
+        user_id: str,
+        file_content: bytes,
+        content_type: str,
+        *,
+        old_avatar_url: str | None,
+    ):
+        _ = (user_id, file_content, content_type, old_avatar_url)
+        url = mock_storage.upload(f"avatars/{uid}.jpg", b"jpeg", "image/jpeg")
         fixed_user.avatar_url = url
         return fixed_user
 
     mock_service = MagicMock(spec=AuthService)
-    mock_service.update_avatar_url = AsyncMock(side_effect=_fake_update_avatar)
+    mock_service.upload_avatar = AsyncMock(side_effect=_fake_upload_avatar)
 
-    app = FastAPI()
+    app = install_test_error_handlers(FastAPI())
     app.include_router(auth_router)
     app.dependency_overrides[get_auth_service] = lambda: mock_service
     app.dependency_overrides[get_current_user] = lambda: fixed_user
 
-    transport = ASGITransport(app=app)
+    transport = ASGITransport(app=app, raise_app_exceptions=False)
     async with AsyncClient(transport=transport, base_url="http://test") as ac:
         r = await ac.post(
             "/api/auth/me/avatar",
@@ -235,8 +243,7 @@ async def test_upload_avatar_cos_calls_storage_and_presigns(
         )
 
     assert r.status_code == 200
-    assert r.json()["avatar_url"] == "https://example.com/signed-avatar"
+    body = r.json()
+    assert body["avatar_url"] == "https://example.com/signed-avatar"
     mock_storage.upload.assert_called_once()
     assert mock_storage.upload.call_args[0][0] == f"avatars/{uid}.jpg"
-    mock_storage.get_url.assert_called_once()
-    assert mock_storage.get_url.call_args[0][0] == f"avatars/{uid}.jpg"