feat: add SMS verification registration with UniSMS provider

- Add phone field to user model with index and helper methods
- Implement SMS provider interface with UniSMS (合一短信) implementation
- Add SMS verification code sending endpoint with rate limiting (1/60s)
- Support SMS registration in Register() (mutually exclusive with email)
- Add SMS configuration to admin settings (provider, keys, signature, template)
- Display phone number in admin user list contact column
- Add i18n translations for all SMS-related messages (zh-CN, en, zh-TW)
- Add Claude Code skills: sync-upstream, migrate-server
- Update CLAUDE.md with git conventions and deployment guide

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

controller/user.go

@@ -157,7 +157,21 @@ func Register(c *gin.Context) {
 			return
 		}
 	}
-	exist, err := model.CheckUserExistOrDeleted(user.Username, user.Email)
+	if common.SMSVerificationEnabled {
+		if user.Phone == "" || user.SmsVerificationCode == "" {
+			common.ApiErrorI18n(c, i18n.MsgUserSmsVerificationRequired)
+			return
+		}
+		if !common.IsValidPhone(user.Phone) {
+			common.ApiErrorI18n(c, i18n.MsgUserPhoneFormatInvalid)
+			return
+		}
+		if !common.VerifyCodeWithKey(user.Phone, user.SmsVerificationCode, common.SmsVerificationPurpose) {
+			common.ApiErrorI18n(c, i18n.MsgUserVerificationCodeError)
+			return
+		}
+	}
+	exist, err := model.CheckUserExistOrDeleted(user.Username, user.Email, user.Phone)
 	if err != nil {
 		common.ApiErrorI18n(c, i18n.MsgDatabaseError)
 		common.SysLog(fmt.Sprintf("CheckUserExistOrDeleted error: %v", err))
@@ -179,6 +193,9 @@ func Register(c *gin.Context) {
 	if common.EmailVerificationEnabled {
 		cleanUser.Email = user.Email
 	}
+	if common.SMSVerificationEnabled {
+		cleanUser.Phone = user.Phone
+	}
 	if err := cleanUser.Insert(inviterId); err != nil {
 		common.ApiError(c, err)
 		return
@@ -390,6 +407,7 @@ func GetSelf(c *gin.Context) {
 		"role":              user.Role,
 		"status":            user.Status,
 		"email":             user.Email,
+		"phone":             user.Phone,
 		"github_id":         user.GitHubId,
 		"discord_id":        user.DiscordId,
 		"oidc_id":           user.OidcId,