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>

members/apps.py

@@ -5,5 +5,4 @@ class MembersConfig(AppConfig):
     name = "members"
 
     def ready(self):
-        # noinspection PyUnusedImports
-        import members.signals
+        import members.signals  # noqa: F401