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>

router/api-router.go

@@ -32,6 +32,7 @@ func SetApiRouter(router *gin.Engine) {
 		apiRouter.GET("/home_page_content", controller.GetHomePageContent)
 		apiRouter.GET("/pricing", middleware.TryUserAuth(), controller.GetPricing)
 		apiRouter.GET("/verification", middleware.EmailVerificationRateLimit(), middleware.TurnstileCheck(), controller.SendEmailVerification)
+		apiRouter.GET("/sms_verification", middleware.SmsVerificationRateLimit(), middleware.TurnstileCheck(), controller.SendSmsVerification)
 		apiRouter.GET("/reset_password", middleware.CriticalRateLimit(), middleware.TurnstileCheck(), controller.SendPasswordResetEmail)
 		apiRouter.POST("/user/reset", middleware.CriticalRateLimit(), controller.ResetPassword)
 		// OAuth routes - specific routes must come before :provider wildcard