fix: 修复管理员更新用户信息时意外覆盖字段的问题

- Enable/IsAdmin/OnlyFirstPurchase 改为 *bool，未传时不更新
- Avatar/Remark/ReferCode/ReferralPercentage 加空值保护
- getDeviceList: 恢复 hifastday@hifast.com 家庭成员受限逻辑

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apis/admin/user.api

@@ -44,13 +44,13 @@ type (
 		Balance            int64  `json:"balance"`
 		Commission         int64  `json:"commission"`
 		ReferralPercentage uint8  `json:"referral_percentage"`
-		OnlyFirstPurchase  bool   `json:"only_first_purchase"`
+		OnlyFirstPurchase  *bool  `json:"only_first_purchase"`
 		GiftAmount         int64  `json:"gift_amount"`
 		Telegram           int64  `json:"telegram"`
 		ReferCode          string `json:"refer_code"`
 		RefererId          int64  `json:"referer_id"`
-		Enable             bool   `json:"enable"`
-		IsAdmin            bool   `json:"is_admin"`
+		Enable             *bool  `json:"enable"`
+		IsAdmin            *bool  `json:"is_admin"`
 		Remark             string `json:"remark"`
 	}
 	UpdateUserNotifySettingRequest {