feat(P1): 成片库按用户维度改造，修复一键生成查不到+越权漏洞

- generated_videos表加user_id列及索引
- 写表时透传user_id（edit_plan_generation + one_take生成）
- /videos接口默认按当前用户查，不传project_id不再查全表
- project_id降级为可选过滤条件
- 补单元测试覆盖user_id过滤逻辑

apps/api/app/api/routes/videos.py

@@ -57,7 +57,7 @@ def _to_video_response(item, storage: OSSStorageService | None = None) -> VideoI
 
 @router.get("/videos", response_model=ListVideosResponse)
 def list_videos(
-    project_id: str | None = Query(None, description="项目ID，不传则返回所有项目"),
+    project_id: str | None = Query(None, description="项目ID，可选过滤"),
     status: str | None = Query(None, description="按状态筛选"),
     review_status: str | None = Query(None, description="按复核状态筛选"),
     page: int = Query(1, ge=1, description="页码"),
@@ -66,9 +66,10 @@ def list_videos(
     storage: OSSStorageService = Depends(get_storage_service),
     current_user: AuthenticatedUser = Depends(get_current_user),
 ):
-    """成片列表，支持分页、按项目/状态/复核状态筛选。"""
+    """成片列表，默认返回当前用户的所有成片，支持按项目/状态/复核状态筛选。"""
     use_case = ListGeneratedVideosPaginatedUseCase(repo)
     items, total = use_case.execute(
+        user_id=current_user.user.id,
         project_id=project_id,
         status=status,
         review_status=review_status,