fix: [menu-sync] 대분류 메뉴 push 시 null URL validation 오류 수정

- import validation에서 url 필드를 required → nullable로 변경
- push/getChildrenData에서 null URL을 빈 문자열로 대체
- importMenu에서 빈 URL을 null로 저장
- push 에러 응답에 원격 서버 에러 메시지 포함

app/Http/Controllers/MenuSyncController.php

@@ -160,7 +160,7 @@ public function import(Request $request): JsonResponse
         $validated = $request->validate([
             'menus' => 'required|array',
             'menus.*.name' => 'required|string|max:100',
-            'menus.*.url' => 'required|string|max:255',
+            'menus.*.url' => 'nullable|string|max:255',
             'menus.*.icon' => 'nullable|string|max:50',
             'menus.*.sort_order' => 'nullable|integer',
             'menus.*.options' => 'nullable|array',
@@ -217,7 +217,7 @@ public function push(Request $request): JsonResponse
 
             return [
                 'name' => $menu->name,
-                'url' => $menu->url,
+                'url' => $menu->url ?? '',
                 'icon' => $menu->icon,
                 'sort_order' => $menu->sort_order,
                 'options' => $menu->options,
@@ -231,7 +231,7 @@ public function push(Request $request): JsonResponse
             $response = Http::withHeaders([
                 'X-Menu-Sync-Key' => $env['api_key'],
                 'Accept' => 'application/json',
-            ])->post(rtrim($env['url'], '/').'/menu-sync/import', [
+            ])->timeout(15)->post(rtrim($env['url'], '/').'/menu-sync/import', [
                 'menus' => $menuData,
             ]);
 
@@ -242,9 +242,11 @@ public function push(Request $request): JsonResponse
                 ]);
             }
 
+            $errorMsg = $response->json('message') ?? $response->json('error') ?? '원격 서버 오류 (HTTP '.$response->status().')';
+
             return response()->json([
-                'error' => $response->json('error', '원격 서버 오류'),
-            ], $response->status());
+                'error' => $errorMsg,
+            ], 422);
         } catch (\Exception $e) {
             return response()->json(['error' => '연결 실패: '.$e->getMessage()], 500);
         }
@@ -380,7 +382,7 @@ private function getChildrenData(int $parentId): array
         return $children->map(function ($menu) {
             return [
                 'name' => $menu->name,
-                'url' => $menu->url,
+                'url' => $menu->url ?? '',
                 'icon' => $menu->icon,
                 'sort_order' => $menu->sort_order,
                 'options' => $menu->options,
@@ -700,7 +702,7 @@ private function importMenu(array $data, ?int $parentId = null): void
                 'parent_id' => $parentId,
             ],
             [
-                'url' => $data['url'],
+                'url' => ! empty($data['url']) ? $data['url'] : null,
                 'icon' => $data['icon'] ?? null,
                 'sort_order' => $data['sort_order'] ?? 0,
                 'options' => $data['options'] ?? null,