Add endpoint to ensure beatmap presence and cache

Introduces a new /beatmaps/ensure API endpoint to verify and cache beatmap metadata and raw files. Updates Playlist model to use auto-incrementing primary key and improves playlist DB insertion logic. Minor formatting and import changes in room and lio modules.

app/database/room.py

@@ -74,6 +74,7 @@ class Room(AsyncAttrs, RoomBase, table=True):
     )
 
 
+
 class RoomResp(RoomBase):
     id: int
     has_password: bool = False