Apply ruff formatting and fix unused import linting errors

Remove unused imports flagged by ruff (F401), apply ruff format across all
files, and restore members.signals side-effect import with noqa: F401 so the
post_save signal that auto-creates Member profiles continues to fire.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

teams/migrations/0001_initial.py

@@ -5,7 +5,6 @@ from django.db import migrations, models
 
 
 class Migration(migrations.Migration):
-
     initial = True
 
     dependencies = []