fix(billing): 保留规则集未覆盖的基础资源价格

apps/api/internal/store/billing_config.go

@@ -17,12 +17,16 @@ type EffectiveBillingConfigInput struct {
 func ResolveEffectiveBillingConfig(input EffectiveBillingConfigInput) map[string]any {
 	config := mergeObjects(input.BaseConfig, nil)
 	if len(input.InheritedRuleSetConfig) > 0 {
-		config = mergeObjects(input.InheritedRuleSetConfig, nil)
+		// Rule sets are allowed to cover only a subset of resource types. Keep
+		// base-model prices for resources that the inherited rule set does not
+		// define, while letting the rule set remain authoritative for matching
+		// top-level keys.
+		config = mergeObjects(config, input.InheritedRuleSetConfig)
 	} else if len(input.LegacyPlatformModelConfig) > 0 {
-		config = mergeObjects(input.LegacyPlatformModelConfig, nil)
+		config = mergeObjects(config, input.LegacyPlatformModelConfig)
 	}
 	if len(input.ModelRuleSetConfig) > 0 {
-		config = mergeObjects(input.ModelRuleSetConfig, nil)
+		config = mergeObjects(config, input.ModelRuleSetConfig)
 	}
 	return mergeObjects(config, input.Override)
 }