fix(offline): delete a finished local game from the device, not the network

The lobby's finished-game delete (hide) always called gateway.hideGame; for a
local (offline) game the transport kill switch refused it, so it toasted and the
game stayed. Route by id: a local game is removed from the device store + the
source cache (LocalSource.delete), an online game still hides on the backend.

ui/src/screens/Lobby.svelte

@@ -14,7 +14,7 @@
   import { getLobby, setLobby } from '../lib/lobbycache';
   import { preloadGames } from '../lib/preload';
   import { kickDictPreload, offlineMode } from '../lib/offline.svelte';
-  import { localSource } from '../lib/gamesource';
+  import { localSource, isLocalGameId } from '../lib/gamesource';
   import { gamePhase, groupGames, orderedSeats, scoreStanding, shouldBlink, type LobbyPhase } from '../lib/lobbysort';
   import type { AccountRef, GameView, Invitation } from '../lib/model';
   import { VARIANT_FLAG, VARIANT_RULES } from '../lib/variants';
@@ -216,7 +216,11 @@
     games = games.filter((g) => g.id !== id); // optimistic; the backend already filters it out
     setLobby({ games, invitations, incoming, atGameLimit });
     try {
-      await gateway.hideGame(id);
+      // A local (offline) game is deleted from the device store; an online game is hidden on the
+      // backend. Routing by id keeps the delete off the network for a local game (the transport
+      // kill switch would otherwise refuse it offline).
+      if (isLocalGameId(id)) await localSource.delete(id);
+      else await gateway.hideGame(id);
     } catch (e) {
       games = prev;
       setLobby({ games, invitations, incoming, atGameLimit });