feat(nudge): name the sender; blink lobby cards; re-animate toasts

The "waiting for your move" popup was the nudge (chat.nudge), shown without a
sender name. Resolve the nudger's per-game seat name server-side and carry it on
a new NudgeEvent.sender_name field, so:

- the in-app toast reads "<opponent>: Waiting for your move 🤭" (chat.nudgeBy);
- the out-of-app Telegram push names the sender too (render nudgeBy);

falling back to the plain phrase when the name is absent (RU mirrored). The
your_turn toast already named the opponent and is unchanged.

Lobby: when a card transitions into "your turn" or "finished" while the lobby is
open, its status emoji blinks twice (two 1s fades); the opponent's-turn change
stays in place. Blink state is keyed by game id (SvelteSet + per-id nonce/timer)
so overlapping events animate in isolation; suppressed under reduce-motion.

Toast: a per-message seq re-keys Toast.svelte, so the freshest toast cancels the
previous one and replays its entrance, uniformly on every screen.

Tests: notify.Nudge round-trip + render named/fallback (Go), game.Service.SeatName
(integration), codec/i18n/gamePhase/shouldBlink (UI). Docs (FUNCTIONAL +_ru,
UI_DESIGN) + PLAN TODO-7 (deferred FLIP card-relocation animation) updated.

pkg/fbs/scrabble.fbs

@@ -606,10 +606,13 @@ table OpponentMovedEvent {
   bag_len:int;
 }
 
-// NudgeEvent signals that a player nudged the recipient.
+// NudgeEvent signals that a player nudged the recipient. sender_name is the nudger's seat
+// display-name snapshot, so the toast and the out-of-app push can name them (added trailing —
+// an older reader still reads just game_id + from_user_id, and falls back to the plain phrase).
 table NudgeEvent {
   game_id:string;
   from_user_id:string;
+  sender_name:string;
 }
 
 // MatchFoundEvent signals that an auto-match pairing (or robot substitution) started a game the