feat: add user roles management UI with owner access control

- Added role management views (list, create, edit, delete)
- Created user_roles URL routing
- Added role management templates with Bootstrap styling
- Updated navbar with Roles link for owners and superusers
- Enhanced decorators and mixins with superuser bypass
- Added assign_owner_role.py utility script

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

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

myproject/user_roles/decorators.py

@@ -20,6 +20,10 @@ def role_required(*role_codes):
             if not request.user.is_authenticated:
                 return redirect('login')
 
+            # Superuser имеет полный доступ
+            if request.user.is_superuser:
+                return view_func(request, *args, **kwargs)
+
             if RoleService.user_has_role(request.user, *role_codes):
                 return view_func(request, *args, **kwargs)