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

packages/application/generated_videos.py

@@ -21,6 +21,7 @@ class ListGeneratedVideosPaginatedUseCase:
     def execute(
         self,
         *,
+        user_id: str | None = None,
         project_id: str | None = None,
         status: str | None = None,
         review_status: str | None = None,
@@ -32,6 +33,7 @@ class ListGeneratedVideosPaginatedUseCase:
         if page_size < 1 or page_size > 100:
             page_size = 20
         return self.generated_video_repository.list_paginated(
+            user_id=user_id,
             project_id=project_id,
             status=status,
             review_status=review_status,