feat：新增大屏存取发布接口

app/datafiles/service.py

@@ -195,7 +195,8 @@ class DataFileService:
 
     async def delete_file(self, user_id: int, file_id: str) -> None:
         await self.get_file(user_id, file_id)
-        await self.store.mark_deleted(file_id)
+        # 同时撤销大屏对它的固定：文件没了，记录不该再停在"永不过期"
+        await self.store.mark_deleted(file_id, datetime.now(UTC) + self._ttl)
         # Windows 上正在查询的 Parquet 删不掉，留给定时清理
         await asyncio.to_thread(shutil.rmtree, self.root / file_id, ignore_errors=True)
 
@@ -215,6 +216,21 @@ class DataFileService:
             raise BizException(404, NOT_FOUND)
         return records
 
+    async def sync_screen_files(
+        self, user_id: int, screen_id: str, file_ids: set[str]
+    ) -> None:
+        """大屏保存后调用：它引用的文件固定住，不再引用的放开（重新按保留时长计时）"""
+        current = await self.store.pinned_ids(screen_id)
+        if added := file_ids - current:
+            await self.store.pin(added, user_id, screen_id)
+        if removed := current - file_ids:
+            await self.store.unpin(screen_id, removed, datetime.now(UTC) + self._ttl)
+
+    async def release_screen_files(self, screen_id: str) -> None:
+        """大屏进回收站或被彻底删除：它固定的文件全部放开"""
+        if current := await self.store.pinned_ids(screen_id):
+            await self.store.unpin(screen_id, current, datetime.now(UTC) + self._ttl)
+
     async def aclose(self) -> None:
         """应用退出时取消还在进行的分析，记录里留下的 pending 下次启动后读取时按失败返回"""
         for task in list(self._tasks):