优化结构

internal/data/payment/provider.go

@@ -0,0 +1,11 @@
+package payment
+
+import (
+	"gorm.io/gorm"
+)
+
+// Provider is the narrow persistence seam required by payment repositories.
+// Keeping it here lets payment remain an independent data module.
+type Provider interface {
+	DB() *gorm.DB
+}