refactor: streamline imports and clean up group access handling in board-related files

backend/app/api/board_memory.py

@@ -6,7 +6,7 @@ from collections.abc import AsyncIterator
 from datetime import datetime, timezone
 from uuid import UUID
 
-from fastapi import APIRouter, Depends, HTTPException, Query, Request, status
+from fastapi import APIRouter, Depends, Query, Request
 from sqlalchemy import func
 from sqlmodel import col, select
 from sqlmodel.ext.asyncio.session import AsyncSession