feat(adtracking): 新增推广链接追踪与数据大盘，支持自定义短码、注册与下单归因及二维码物料生成

1. 数据库新增 000064_ad_tracking.sql 迁移，创建 ad_tracking_links 和 ad_tracking_clicks 表，并在 users、rental_orders 增加归因字段
2. 后端新增 adtracking 模块，挂载 GET /r/:code 302 智能重定向、点击流水异步记录、转化率/GMV聚合统计及管理接口
3. 用户认证 (auth) 与订单创建 (order) 链路贯通，实现注册用户与订单成交推广短码全链路归因
4. 前端管理后台左侧新增【推广追踪】目录，支持大盘指标总览、推广链接 CRUD、状态启停、一键复制短链及二维码下载 (PNG)

backend/internal/modules/auth/repository.go

@@ -3,6 +3,7 @@ package auth
 import (
 	"context"
 	"errors"
+	"strings"
 	"time"
 
 	"hfb_sys/backend/internal/model"
@@ -57,16 +58,21 @@ func (r *UserRepository) UpdateProfile(ctx context.Context, id uint64, nickname
 	return r.FindByID(ctx, id)
 }
 
-func (r *UserRepository) FindOrCreateByPhone(ctx context.Context, phone string) (*model.User, error) {
+func (r *UserRepository) FindOrCreateByPhone(ctx context.Context, phone string, trackCode ...string) (*model.User, error) {
 	now := time.Now()
+	var code string
+	if len(trackCode) > 0 {
+		code = strings.TrimSpace(trackCode[0])
+	}
 	user := model.User{
-		Phone:          phone,
-		Nickname:       "用户" + phone[len(phone)-4:],
-		RealnameStatus: "unverified",
-		RiskStatus:     "normal",
-		CreditScore:    100,
-		Status:         "active",
-		LastLoginAt:    &now,
+		Phone:             phone,
+		Nickname:          "用户" + phone[len(phone)-4:],
+		RealnameStatus:    "unverified",
+		RiskStatus:        "normal",
+		CreditScore:       100,
+		Status:            "active",
+		RegisterTrackCode: code,
+		LastLoginAt:       &now,
 	}
 
 	err := r.db.WithContext(ctx).Clauses(clause.OnConflict{
@@ -96,17 +102,22 @@ func (r *UserRepository) SetPassword(ctx context.Context, userID uint64, hash st
 	return r.db.WithContext(ctx).Model(&model.User{}).Where("id = ?", userID).Update("password_hash", hash).Error
 }
 
-func (r *UserRepository) RegisterWithPassword(ctx context.Context, phone string, hash string) (*model.User, error) {
+func (r *UserRepository) RegisterWithPassword(ctx context.Context, phone string, hash string, trackCode ...string) (*model.User, error) {
 	now := time.Now()
+	var code string
+	if len(trackCode) > 0 {
+		code = strings.TrimSpace(trackCode[0])
+	}
 	user := model.User{
-		Phone:          phone,
-		PasswordHash:   hash,
-		Nickname:       "用户" + phone[len(phone)-4:],
-		RealnameStatus: "unverified",
-		RiskStatus:     "normal",
-		CreditScore:    100,
-		Status:         "active",
-		LastLoginAt:    &now,
+		Phone:             phone,
+		PasswordHash:      hash,
+		Nickname:          "用户" + phone[len(phone)-4:],
+		RealnameStatus:    "unverified",
+		RiskStatus:        "normal",
+		CreditScore:       100,
+		Status:            "active",
+		RegisterTrackCode: code,
+		LastLoginAt:       &now,
 	}
 
 	err := r.db.WithContext(ctx).Create(&user).Error