feat(phase6): 测试补全 + 集成测试 + repository 落地示范

- tests/unit/modules/test_repository.py：base_repository 在 SQLite 内存库的 CRUD 测试
- tests/integration/api/test_smoke.py：登录链路 / 只读接口 / 未授权拦截（标记 integration，默认跳过）
- conftest 提供 sqlite_db（隔离 DB）与 app/client/admin_headers（集成）fixture
- pytest.ini 默认跳过 integration，Makefile test-integration 可显式运行
- 修复 base_repository.get_by_id/get_by_ids 对字符串 ID 的兼容（URL 路径参数）
- 示范 modules/system/level service 改用 level_repo，CRUD 全链路实测通过

Co-Authored-By: Claude <noreply@anthropic.com>

shared/base_repository.py

@@ -42,8 +42,14 @@ class BaseRepository(Generic[M]):
     # ============================================================
 
     def get_by_id(self, obj_id: Optional[int]) -> Optional[M]:
-        """根据ID获取未删除记录。"""
-        if obj_id is None or obj_id <= 0:
+        """根据ID获取未删除记录（兼容字符串ID，如 URL 路径参数）。"""
+        if obj_id is None or obj_id == '':
+            return None
+        try:
+            obj_id = int(obj_id)
+        except (TypeError, ValueError):
+            return None
+        if obj_id <= 0:
             return None
         return self.db.query(self.model).filter(
             self.model.id == obj_id, self._soft_col() == 0
@@ -51,7 +57,14 @@ class BaseRepository(Generic[M]):
 
     def get_by_ids(self, ids) -> list:
         """根据ID列表批量获取未删除记录。"""
-        valid = [i for i in ids if i and i > 0]
+        valid = []
+        for i in ids:
+            try:
+                i = int(i)
+            except (TypeError, ValueError):
+                continue
+            if i > 0:
+                valid.append(i)
         if not valid:
             return []
         return self.db.query(self.model).filter(