style: dart format 적용

- 전체 Dart 소스 및 테스트 파일 포매팅 통일
- trailing comma, 줄바꿈, 인덴트 정리

lib/src/core/engine/iap_service.dart

@@ -131,9 +131,7 @@ class IAPService {
     final response = await _iap.queryProductDetails(IAPProductIds.all);
 
     if (response.notFoundIDs.isNotEmpty) {
-      debugPrint(
-        '[IAPService] Products not found: ${response.notFoundIDs}',
-      );
+      debugPrint('[IAPService] Products not found: ${response.notFoundIDs}');
     }
 
     for (final product in response.productDetails) {
@@ -238,14 +236,10 @@ class IAPService {
     }
 
     // 구매 요청
-    final purchaseParam = PurchaseParam(
-      productDetails: _removeAdsProduct!,
-    );
+    final purchaseParam = PurchaseParam(productDetails: _removeAdsProduct!);
 
     try {
-      final success = await _iap.buyNonConsumable(
-        purchaseParam: purchaseParam,
-      );
+      final success = await _iap.buyNonConsumable(purchaseParam: purchaseParam);
       debugPrint('[IAPService] Purchase initiated: $success');
       return success ? IAPResult.success : IAPResult.failed;
     } catch (e) {