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.

PLAN.md

@@ -1589,3 +1589,9 @@ cannot submit; three-way admin filter.
   `account_stats` or a games query), falling back to their interface language
   (en → English, ru → Russian/Эрудит). Until then the explicit pick avoids guessing
   wrong.
+- **TODO-7 — animate a lobby card's move between sections (owner's idea, 2026-06).**
+  When a game changes bucket — *your turn* → *finished*, *opponent's turn* → *your turn*, etc. —
+  its card simply re-renders in the new section; only the status emoji **blinks twice** (added
+  alongside the named-nudge + lobby-blink work). A FLIP / slide animation that visibly relocates
+  the card to its new section would be a nicer touch. Deferred — purely cosmetic, nothing depends
+  on it.