chore: fix all ruff lint warnings (unused imports, unsorted imports, unused vars)

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

web/tests/test_roles.py

@@ -5,14 +5,13 @@ and admin route protection.
 import pytest
 from quart import Blueprint
 
+from beanflows import core
 from beanflows.auth.routes import (
     ensure_admin_role,
     grant_role,
     revoke_role,
     role_required,
 )
-from beanflows import core
-
 
 # ════════════════════════════════════════════════════════════
 # grant_role / revoke_role