feat: 添加管理员权限管理功能，更新 AdminUser 模型以支持权限加载，扩展 API 路由以管理后台用户及其权限

app/Http/Controllers/Api/V1/Admin/User/AdminUserIndexController.php

@@ -0,0 +1,65 @@
+<?php
+
+namespace App\Http\Controllers\Api\V1\Admin\User;
+
+use App\Http\Controllers\Controller;
+use App\Models\AdminUser;
+use App\Support\ApiResponse;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+
+/** GET /api/v1/admin/admin-users */
+final class AdminUserIndexController extends Controller
+{
+    public function __invoke(Request $request): JsonResponse
+    {
+        $perPage = min(max((int) $request->integer('per_page', 25), 1), 100);
+        $page = max((int) $request->integer('page', 1), 1);
+        $keyword = trim((string) $request->query('keyword', ''));
+
+        $q = AdminUser::query()
+            ->with(['roles.permissions', 'permissions'])
+            ->orderByDesc('id');
+
+        if ($keyword !== '') {
+            $q->where(function ($sub) use ($keyword): void {
+                $sub->where('username', 'like', '%'.$keyword.'%')
+                    ->orWhere('name', 'like', '%'.$keyword.'%')
+                    ->orWhere('email', 'like', '%'.$keyword.'%');
+            });
+        }
+
+        $paginator = $q->paginate($perPage, ['*'], 'page', $page);
+
+        return ApiResponse::success([
+            'items' => collect($paginator->items())->map(
+                fn (AdminUser $user): array => $this->row($user)
+            )->all(),
+            'meta' => [
+                'current_page' => $paginator->currentPage(),
+                'per_page' => $paginator->perPage(),
+                'total' => $paginator->total(),
+                'last_page' => $paginator->lastPage(),
+            ],
+        ]);
+    }
+
+    /** @return array<string, mixed> */
+    private function row(AdminUser $user): array
+    {
+        return [
+            'id' => (int) $user->id,
+            'username' => $user->username,
+            'nickname' => $user->name,
+            'email' => $user->email,
+            'status' => (int) $user->status,
+            'roles' => $user->adminRoleSlugs(),
+            'direct_permissions' => $user->permissions
+                ->pluck('slug')
+                ->filter(static fn ($slug): bool => is_string($slug) && $slug !== '')
+                ->values()
+                ->all(),
+            'effective_permissions' => $user->adminPermissionSlugs(),
+        ];
+    }
+}