为 9 个模块添加 Context 超时控制

完成模块：
- auth: 3 个 Repository 方法 + Service + Handler + Middleware
- wallet: 已有 context 支持，修复依赖调用
- payment: 已有 context 支持，修复 wallet 调用
- adminaudit: 1 个方法
- notification: 2 个方法
- realname: 2 个方法
- systemconfig: 4 个方法
- adminauth: 7 个方法
- adminuser: 6 个方法

所有数据库调用已改为 r.db.WithContext(ctx)，完整传递 context 链路。

待完成模块: order, listing, chat 等 12 个模块（约 157 个方法）

backend/internal/modules/adminaudit/repository.go

@@ -1,6 +1,7 @@
 package adminaudit
 
 import (
+	"context"
 	"time"
 
 	"hfb_sys/backend/internal/model"
@@ -17,14 +18,14 @@ func NewRepository(db *gorm.DB) *Repository {
 	return &Repository{db: db}
 }
 
-func (r *Repository) List(query Query) (*PaginatedResult, error) {
-	db := r.db.Table("audit_logs AS al").
+func (r *Repository) List(ctx context.Context, query Query) (*PaginatedResult, error) {
+	db := r.db.WithContext(ctx).Table("audit_logs AS al").
 		Select(`al.id, al.actor_type, al.actor_id, COALESCE(au.username, '') AS actor_username,
 			COALESCE(au.nickname, '') AS actor_nickname, al.action, al.biz_type, al.biz_id,
 			al.ip, al.user_agent, al.detail, al.created_at`).
 		Joins("LEFT JOIN admin_users AS au ON au.id = al.actor_id AND al.actor_type = ?", "admin")
 
-	countDB := r.db.Model(&model.AuditLog{})
+	countDB := r.db.WithContext(ctx).Model(&model.AuditLog{})
 	if query.ActorID > 0 {
 		db = db.Where("al.actor_id = ?", query.ActorID)
 		countDB = countDB.Where("actor_id = ?", query.ActorID)