新增支付配置备份导出功能

backend/internal/modules/paymentconfig/repository.go

@@ -153,6 +153,45 @@ func (r *Repository) FindByProviderMerchant(provider string, merchantID string,
 	return &dto, nil
 }
 
+// ExportBackup 导出所有支付配置备份，包含解密后的密钥。
+func (r *Repository) ExportBackup(actorID uint64, meta AuditMeta) (*ExportBackup, error) {
+	var backup *ExportBackup
+	err := r.db.Transaction(func(tx *gorm.DB) error {
+		var items []model.PaymentMerchantConfig
+		if err := tx.Order("is_default DESC, id DESC").Find(&items).Error; err != nil {
+			return err
+		}
+
+		configs := make([]ConfigDTO, 0, len(items))
+		for _, item := range items {
+			dto, err := r.toDTO(item, true)
+			if err != nil {
+				return err
+			}
+			configs = append(configs, dto)
+		}
+
+		exportedAt := time.Now().Format(time.RFC3339)
+		backup = &ExportBackup{
+			Type:       "payment_config_backup",
+			Version:    1,
+			ExportedAt: exportedAt,
+			ExportedBy: actorID,
+			Total:      len(configs),
+			Configs:    configs,
+		}
+
+		return appendAuditLog(tx, actorID, "payment_config.export", 0, meta, map[string]any{
+			"total":       len(configs),
+			"exported_at": exportedAt,
+		})
+	})
+	if err != nil {
+		return nil, err
+	}
+	return backup, nil
+}
+
 // FindActiveByProvider 查询提供商的所有激活配置
 func (r *Repository) FindActiveByProvider(provider string) ([]model.PaymentMerchantConfig, error) {
 	var items []model.PaymentMerchantConfig