新增摸大红业务并修复后台链接按钮白字

支持分类筛选、搜索、下单支付建群与固定二维码；合并迁移种子数据；后台表格编辑/详情链接恢复主题色可见。

backend/internal/modules/mohong/config.go

@@ -0,0 +1,117 @@
+package mohong
+
+import (
+	"context"
+	"strings"
+
+	"hfb_sys/backend/internal/model"
+
+	"gorm.io/gorm"
+	"gorm.io/gorm/clause"
+)
+
+const (
+	configKeyDefaultQrcodeURL  = "mohong.default_qrcode_url"
+	configKeyGroupWelcomeText  = "mohong.group_welcome_text"
+	configKeyOrderCopyTemplate = "mohong.order_copy_template"
+
+	defaultGroupWelcomeText = "订单已支付，请扫码联系客服，并将下方订单信息复制发送给客服。"
+	defaultOrderCopyTemplate = "【摸大红订单】\n订单号：{{order_no}}\n下单时间：{{created_at}}\n商品：{{product_title}}\n数量：{{quantity}}\n金额：{{amount}}\n下单人：{{buyer_name}}（{{buyer_phone}}）"
+)
+
+func (r *Repository) GetConfig(ctx context.Context) (*ConfigDTO, error) {
+	if r.db == nil {
+		return nil, ErrDependencyUnavailable
+	}
+	keys := []string{configKeyDefaultQrcodeURL, configKeyGroupWelcomeText, configKeyOrderCopyTemplate}
+	var rows []model.SystemConfig
+	if err := r.db.WithContext(ctx).Where("`key` IN ?", keys).Find(&rows).Error; err != nil {
+		return nil, err
+	}
+	values := map[string]string{}
+	for _, row := range rows {
+		values[row.Key] = row.Value
+	}
+	return &ConfigDTO{
+		DefaultQrcodeURL:  strings.TrimSpace(values[configKeyDefaultQrcodeURL]),
+		GroupWelcomeText:  firstNonEmpty(values[configKeyGroupWelcomeText], defaultGroupWelcomeText),
+		OrderCopyTemplate: firstNonEmpty(values[configKeyOrderCopyTemplate], defaultOrderCopyTemplate),
+	}, nil
+}
+
+func (r *Repository) UpdateConfig(ctx context.Context, req UpdateConfigRequest) (*ConfigDTO, error) {
+	if r.db == nil {
+		return nil, ErrDependencyUnavailable
+	}
+	err := r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
+		if req.DefaultQrcodeURL != nil {
+			if err := upsertConfig(tx, configKeyDefaultQrcodeURL, strings.TrimSpace(*req.DefaultQrcodeURL), "摸大红全局默认固定二维码图片URL"); err != nil {
+				return err
+			}
+		}
+		if req.GroupWelcomeText != nil {
+			if err := upsertConfig(tx, configKeyGroupWelcomeText, strings.TrimSpace(*req.GroupWelcomeText), "摸大红订单群欢迎语"); err != nil {
+				return err
+			}
+		}
+		if req.OrderCopyTemplate != nil {
+			if err := upsertConfig(tx, configKeyOrderCopyTemplate, strings.TrimSpace(*req.OrderCopyTemplate), "摸大红订单一键复制文案模板"); err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	return r.GetConfig(ctx)
+}
+
+func upsertConfig(tx *gorm.DB, key, value, description string) error {
+	row := model.SystemConfig{
+		Key:         key,
+		Value:       value,
+		Description: description,
+	}
+	return tx.Clauses(clause.OnConflict{
+		Columns:   []clause.Column{{Name: "key"}},
+		DoUpdates: clause.AssignmentColumns([]string{"value", "description"}),
+	}).Create(&row).Error
+}
+
+func firstNonEmpty(values ...string) string {
+	for _, v := range values {
+		if strings.TrimSpace(v) != "" {
+			return strings.TrimSpace(v)
+		}
+	}
+	return ""
+}
+
+func (r *Repository) resolveQrcodeURL(tx *gorm.DB, productQrcode string) string {
+	productQrcode = strings.TrimSpace(productQrcode)
+	if productQrcode != "" {
+		return productQrcode
+	}
+	var cfg model.SystemConfig
+	if err := tx.Where("`key` = ?", configKeyDefaultQrcodeURL).First(&cfg).Error; err == nil {
+		return strings.TrimSpace(cfg.Value)
+	}
+	return ""
+}
+
+func (r *Repository) loadWelcomeText(tx *gorm.DB) string {
+	var cfg model.SystemConfig
+	if err := tx.Where("`key` = ?", configKeyGroupWelcomeText).First(&cfg).Error; err == nil && strings.TrimSpace(cfg.Value) != "" {
+		return strings.TrimSpace(cfg.Value)
+	}
+	return defaultGroupWelcomeText
+}
+
+func (r *Repository) loadCopyTemplate(tx *gorm.DB) string {
+	var cfg model.SystemConfig
+	if err := tx.Where("`key` = ?", configKeyOrderCopyTemplate).First(&cfg).Error; err == nil && strings.TrimSpace(cfg.Value) != "" {
+		return strings.TrimSpace(cfg.Value)
+	}
+	return defaultOrderCopyTemplate
+}