fix: add type annotation for status_codes in concurrent test

Added explicit type annotation `list[int]` to fix ty type checker error
in test_concurrent_guild_creation_same_id. This resolves the
unsupported-operator error when comparing with 400.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: JacobCoffee

tests/integration/test_api_endpoints.py

@@ -363,7 +363,7 @@ async def test_concurrent_guild_creation_same_id(
         results = await asyncio.gather(*tasks, return_exceptions=True)
 
         # One should succeed (201), one should fail (409 or 500)
-        status_codes = [r.status_code if hasattr(r, "status_code") else 500 for r in results]  # type: ignore[misc]
+        status_codes: list[int] = [r.status_code if hasattr(r, "status_code") else 500 for r in results]  # type: ignore[misc]
         assert HTTP_201_CREATED in status_codes
         # At least one should indicate a conflict/error
         assert any(code >= 400 for code in status_codes)