feat(gateway): confirmEmailLink RPC + language on the email request + profile event

Add the confirm-link edge method (auth.email.confirm_link): a new
EmailConfirmLinkRequest/Result fbs table, the transcode const + handler + encoder,
and the backend-client call to the existing /sessions/email/confirm-link endpoint —
it rides Execute under the existing service prefix, so no proto/Caddy change. Add a
language field to EmailRequestRequest and forward it (the backend already seeds it).
Add the NotifyProfile sub-kind + notify.ProfileChanged, published by the confirm-link
handler on a successful link so an in-app session re-fetches its profile when the
email was confirmed in another browser. Regenerated fbs bindings (Go + TS).

backend/internal/notify/events.go

@@ -155,6 +155,13 @@ func Notification(userID uuid.UUID, kind string) Intent {
 	return Intent{UserID: userID, Kind: KindNotification, Payload: b.FinishedBytes(), EventID: eventID()}
 }
 
+// ProfileChanged is a payload-free "re-fetch your profile" signal to userID, emitted
+// when the viewer's own account changed out of band — an email confirmed through the
+// one-tap deeplink opened in another browser.
+func ProfileChanged(userID uuid.UUID) Intent {
+	return Notification(userID, NotifyProfile)
+}
+
 // NotificationAccount builds a lobby notification of one of the friend_* kinds carrying the
 // account it concerns (the requester, the new friend or the decliner), so the client updates its
 // requests/friends lists and the in-game "add friend" state without a refetch.

backend/internal/notify/notify.go

@@ -69,6 +69,10 @@ const (
 	// it re-fetches profile.get to show or hide the banner. It carries no payload (the
 	// banner set rides the profile response). In-app only.
 	NotifyBanner = "banner"
+	// NotifyProfile tells the client that the viewer's own profile changed out of band
+	// (e.g. an email was confirmed via the one-tap deeplink opened in another browser),
+	// so it re-fetches profile.get. It carries no payload. In-app only.
+	NotifyProfile = "profile"
 	// NotifyUserBlocked confirms to the blocker that a per-user block took effect,
 	// carrying the blocked account, so every one of the blocker's sessions updates the
 	// in-game block/add-friend controls and the struck name in place. It is delivered

backend/internal/server/handlers_auth.go

@@ -9,6 +9,7 @@ import (
 	"go.uber.org/zap"
 
 	"scrabble/backend/internal/account"
+	"scrabble/backend/internal/notify"
 )
 
 // The /api/v1/internal/sessions/* endpoints are gateway-only: the gateway has
@@ -252,11 +253,14 @@ func (s *Server) handleEmailConfirmLink(c *gin.Context) {
 		c.JSON(http.StatusOK, confirmLinkResponse{Purpose: "login", Status: "confirmed", Session: &sess})
 		return
 	}
-	status := "confirmed"
 	if res.NeedsMerge {
-		status = "merge_required"
+		c.JSON(http.StatusOK, confirmLinkResponse{Purpose: "link", Status: "merge_required"})
+		return
 	}
-	c.JSON(http.StatusOK, confirmLinkResponse{Purpose: "link", Status: status})
+	// A free link attached the email; nudge the account's in-app session(s) to re-fetch
+	// the profile, so a link confirmed in another browser reflects at once.
+	s.notifier.Publish(notify.ProfileChanged(res.Account))
+	c.JSON(http.StatusOK, confirmLinkResponse{Purpose: "link", Status: "confirmed"})
 }
 
 // tokenRequest carries an opaque session token.