perf: optimize get_notes_by_user_id to reduce database queries

- Replace inefficient memory-based filtering with database-level filtering
- Add proper access control conditions to SQL query
- Reduce memory usage by filtering at database level instead of loading all notes
- Maintain access control validation with post-filtering for complex cases

This change significantly improves performance for users with many notes
by reducing the number of database queries and memory usage.

Signed-off-by: Sihyeon Jang <sihyeon.jang@navercorp.com>

backend/open_webui/routers/notes.py

@@ -48,7 +48,7 @@ async def get_notes(request: Request, user=Depends(get_verified_user)):
                 "user": UserResponse(**Users.get_user_by_id(note.user_id).model_dump()),
             }
         )
-        for note in Notes.get_notes_by_user_id(user.id, "write")
+        for note in Notes.get_notes_by_access(user.id, "write")
     ]
 
     return notes
@@ -81,7 +81,7 @@ async def get_note_list(
 
     notes = [
         NoteTitleIdResponse(**note.model_dump())
-        for note in Notes.get_notes_by_user_id(user.id, "write", skip=skip, limit=limit)
+        for note in Notes.get_notes_by_access(user.id, "write", skip=skip, limit=limit)
     ]
 
     return notes