Refactor test files for improved readability and consistency

- Removed unnecessary blank lines and adjusted formatting in test files.
- Ensured consistent use of commas in function calls and assertions across various test cases.
- Updated import statements for better organization and clarity.
- Enhanced mock setups in tests for better isolation and reliability.
- Improved assertions to follow a consistent style for better readability.

app/api/v1/player.py

@@ -1,6 +1,6 @@
 """Player API endpoints."""
 
-from typing import Annotated, Any
+from typing import Annotated
 
 from fastapi import APIRouter, Depends, HTTPException, status
 
@@ -214,4 +214,4 @@ async def get_state(
         raise HTTPException(
             status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
             detail="Failed to get player state",
-        ) from e
+        ) from e