refactor: reorganize import statements and improve code formatting across multiple files

backend/app/api/boards.py

@@ -3,8 +3,7 @@
 from __future__ import annotations
 
 from enum import Enum
-from typing import TYPE_CHECKING, Literal
-from typing import cast
+from typing import TYPE_CHECKING, Literal, cast
 from uuid import UUID
 
 from fastapi import APIRouter, Depends, HTTPException, Query, status