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/codec.ts

@@ -537,7 +537,7 @@ export function decodeEvent(kind: string, payload: Uint8Array): PushEvent | null
       return { kind: 'chat_message', message: decodeChatMsg(fb.ChatMessage.getRootAsChatMessage(bb)) };
     case 'nudge': {
       const e = fb.NudgeEvent.getRootAsNudgeEvent(bb);
-      return { kind: 'nudge', gameId: s(e.gameId()), fromUserId: s(e.fromUserId()) };
+      return { kind: 'nudge', gameId: s(e.gameId()), fromUserId: s(e.fromUserId()), senderName: s(e.senderName()) };
     }
     case 'match_found': {
       const e = fb.MatchFoundEvent.getRootAsMatchFoundEvent(bb);