Ignore conversation updates that arrive soon after marking as spam

Apparently there are race conditions in the gmessages app where it may
send a `SPAM_FOLDER` update and then `ACTIVE` immediately afterwards.

portal.go

@@ -288,6 +288,7 @@ type Portal struct {
 	matrixMessages chan PortalMatrixMessage
 
 	cancelCreation atomic.Pointer[context.CancelCauseFunc]
+	markedSpamAt   time.Time
 }
 
 var (

user.go

@@ -1119,6 +1119,9 @@ func (user *User) syncConversation(v *gmproto.Conversation, source string) {
 		Logger()
 	log.Debug().Any("conversation_data", convCopy).Msg("Got conversation update")
 	ctx := log.WithContext(context.TODO())
+	if updateType == gmproto.ConversationStatus_SPAM_FOLDER || updateType == gmproto.ConversationStatus_BLOCKED_FOLDER {
+		portal.markedSpamAt = time.Now()
+	}
 	if cancel := portal.cancelCreation.Load(); cancel != nil {
 		if updateType == gmproto.ConversationStatus_SPAM_FOLDER || updateType == gmproto.ConversationStatus_BLOCKED_FOLDER {
 			(*cancel)(fmt.Errorf("conversation was moved to spam"))
@@ -1161,6 +1164,9 @@ func (user *User) syncConversation(v *gmproto.Conversation, source string) {
 		if v.Participants == nil {
 			log.Debug().Msg("Not syncing conversation with nil participants")
 			return
+		} else if time.Since(portal.markedSpamAt) < 1*time.Minute {
+			log.Warn().Msg("Dropping conversation update due to suspected race condition")
+			return
 		}
 		if source == "event" {
 			go func() {