feat(pricing): 단가관리 stats, bulkDestroy API 추가

- GET /pricing/stats: 단가 통계 조회 (total, draft, finalized, expired)
- DELETE /pricing/bulk: 단가 일괄 삭제 (확정된 단가 제외)
- PriceBulkDeleteRequest FormRequest 추가
- PricingService.stats(), bulkDestroy() 메서드 구현

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

app/Http/Controllers/Api/V1/PricingController.php

@@ -4,6 +4,7 @@
 
 use App\Helpers\ApiResponse;
 use App\Http\Controllers\Controller;
+use App\Http\Requests\Pricing\PriceBulkDeleteRequest;
 use App\Http\Requests\Pricing\PriceByItemsRequest;
 use App\Http\Requests\Pricing\PriceCostRequest;
 use App\Http\Requests\Pricing\PriceIndexRequest;
@@ -124,4 +125,29 @@ public function cost(PriceCostRequest $request)
             return ['data' => $data, 'message' => __('message.fetched')];
         });
     }
+
+    /**
+     * 단가 통계 조회
+     */
+    public function stats()
+    {
+        return ApiResponse::handle(function () {
+            $data = $this->service->stats();
+
+            return ['data' => $data, 'message' => __('message.fetched')];
+        });
+    }
+
+    /**
+     * 단가 일괄 삭제
+     */
+    public function bulkDestroy(PriceBulkDeleteRequest $request)
+    {
+        return ApiResponse::handle(function () use ($request) {
+            $validated = $request->validated();
+            $deletedCount = $this->service->bulkDestroy($validated['ids']);
+
+            return ['data' => ['deleted_count' => $deletedCount], 'message' => __('message.deleted')];
+        });
+    }
 }