chore: 将后端移动到 api/ 目录，准备合并为单仓库

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

api/account/decorators.py

@@ -0,0 +1,28 @@
+from ninja import NinjaAPI
+from functools import wraps
+from typing import Callable, List, Any
+from django.http import HttpRequest
+from django.contrib.auth.decorators import login_required, user_passes_test
+from .models import User, RoleChoices
+
+api = NinjaAPI()
+
+
+def _require(roles: List[RoleChoices]) -> Callable:
+    def check_role(user: User) -> bool:
+        return user.is_authenticated and hasattr(user, "role") and user.role in roles
+
+    def decorator(func: Callable) -> Callable:
+        @wraps(func)
+        @login_required
+        @user_passes_test(check_role, login_url=None)
+        def wrapper(request: HttpRequest, *args: Any, **kwargs: Any) -> Any:
+            return func(request, *args, **kwargs)
+
+        return wrapper
+
+    return decorator
+
+
+admin_required = _require([RoleChoices.ADMIN, RoleChoices.SUPER])
+super_required = _require([RoleChoices.SUPER])