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.

ui/src/lib/i18n/en.ts

@@ -114,7 +114,8 @@ export const en = {
 
   'chat.placeholder': 'Quick message…',
   'chat.send': 'Send',
-  'chat.nudge': 'Waiting for your move!',
+  'chat.nudge': 'Waiting for your move 🤭',
+  'chat.nudgeBy': '{name}: Waiting for your move 🤭',
   'chat.nudgeAction': 'Nudge',
   'chat.awaitingReply': "Waiting for the opponent's reply",
   'chat.empty': 'No messages yet.',

ui/src/lib/i18n/ru.ts

@@ -115,7 +115,8 @@ export const ru: Record<MessageKey, string> = {
 
   'chat.placeholder': 'Короткое сообщение…',
   'chat.send': 'Отправить',
-  'chat.nudge': 'Жду вашего хода!',
+  'chat.nudge': 'Жду Вашего хода 🤭',
+  'chat.nudgeBy': '{name}: Жду Вашего хода 🤭',
   'chat.nudgeAction': 'Поторопить',
   'chat.awaitingReply': 'Ждём реакцию соперника',
   'chat.empty': 'Сообщений пока нет.',