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>

common/sms_unisms.go

@@ -0,0 +1,22 @@
+package common
+
+import (
+	unisms "github.com/apistd/uni-go-sdk/sms"
+)
+
+type UniSmsProvider struct{}
+
+func (p *UniSmsProvider) SendCode(phone string, code string) error {
+	client := unisms.NewClient(SMSAccessKeyId, SMSAccessKeySecret)
+	message := unisms.BuildMessage()
+	message.SetTo(phone)
+	message.SetSignature(SMSSignName)
+	message.SetTemplateId(SMSTemplateCode)
+	message.SetTemplateData(map[string]string{"code": code})
+	_, err := client.Send(message)
+	return err
+}
+
+func init() {
+	RegisterSmsProvider("unisms", &UniSmsProvider{})
+}