修复：调整游客取号限流策略

问题：移动网络共享出口 IP 会造成游客取号被误限流。

实现：移除公开取号 IP 限制，改用项目总量与手机号 HMAC 限流，并支持 Retry-After 倒计时。

server/internal/httpapi/public.go

@@ -60,12 +60,6 @@ func (s *Server) publicCreateTicket(w http.ResponseWriter, r *http.Request) {
 		writeError(w, err)
 		return
 	}
-	if s.publicTicketLimiter != nil {
-		if allowed, retry := s.publicTicketLimiter.allow("ip:" + publicQueryClientKey(r)); !allowed {
-			writePublicTicketRateLimit(w, retry)
-			return
-		}
-	}
 	var actor model.User
 	if err := s.db.WithContext(r.Context()).Where("username = ?", model.PublicVisitorUsername).First(&actor).Error; err != nil {
 		writeError(w, err)
@@ -74,6 +68,21 @@ func (s *Server) publicCreateTicket(w http.ResponseWriter, r *http.Request) {
 	s.createTicketForActor(w, r, actor.ID, true)
 }
 
+func publicTicketProjectLimitKey(projectID string) string {
+	return "project:" + projectID
+}
+
+func publicTicketPhoneLimitKey(projectID, phoneDigest string) string {
+	return "project:" + projectID + ":phone:" + phoneDigest
+}
+
+func (s *Server) allowPublicTicket(projectID, phoneDigest string) (bool, time.Duration) {
+	if allowed, retry := s.publicTicketProjectLimiter.allow(publicTicketProjectLimitKey(projectID)); !allowed {
+		return false, retry
+	}
+	return s.publicTicketPhoneLimiter.allow(publicTicketPhoneLimitKey(projectID, phoneDigest))
+}
+
 type publicPhoneQueryRequest struct {
 	Phone string `json:"phone"`
 }