feat(payment): 优化套餐配置和支付服务

- 简化套餐配置结构，删除冗余的 default.yaml 和 us.yaml
- 优化 Apple IAP 服务和验证逻辑
- 更新套餐数据模型和协议文档
- 添加支付相关测试用例

apps/lib/features/points/data/models/package_info.dart

@@ -1,4 +1,4 @@
-enum ProductCode { newUserPack, basicPack, popularPack, premiumPack }
+enum ProductCode { newUserPack, starterPack, popularPack, premiumPack }
 
 enum PackageType { starter, regular }
 
@@ -7,7 +7,6 @@ class PackageInfo {
     required this.productCode,
     required this.appStoreProductId,
     required this.type,
-    required this.price,
     required this.credits,
     required this.isStarter,
     required this.starterEligible,
@@ -17,7 +16,6 @@ class PackageInfo {
   final ProductCode productCode;
   final String appStoreProductId;
   final PackageType type;
-  final double price;
   final int credits;
   final bool isStarter;
   final bool starterEligible;
@@ -30,7 +28,6 @@ class PackageInfo {
       type: json['type'] == 'starter'
           ? PackageType.starter
           : PackageType.regular,
-      price: (json['price'] as num).toDouble(),
       credits: json['credits'] as int,
       isStarter: json['isStarter'] as bool,
       starterEligible: json['starterEligible'] as bool,
@@ -41,31 +38,23 @@ class PackageInfo {
   static ProductCode _parseProductCode(String code) {
     return switch (code) {
       'new_user_pack' => ProductCode.newUserPack,
-      'basic_pack' => ProductCode.basicPack,
+      'starter_pack' => ProductCode.starterPack,
       'popular_pack' => ProductCode.popularPack,
       'premium_pack' => ProductCode.premiumPack,
       _ => throw ArgumentError('Unknown product code: $code'),
     };
   }
-
-  String get priceDisplay => '\$${price.toStringAsFixed(2)}';
 }
 
 class PackagesResult {
   const PackagesResult({
-    required this.region,
-    required this.currency,
     required this.packages,
   });
 
-  final String region;
-  final String currency;
   final List<PackageInfo> packages;
 
   factory PackagesResult.fromJson(Map<String, dynamic> json) {
     return PackagesResult(
-      region: json['region'] as String,
-      currency: json['currency'] as String,
       packages: (json['packages'] as List<dynamic>)
           .map((e) => PackageInfo.fromJson(e as Map<String, dynamic>))
           .toList(),