fix(client): wrap connect/disconnect in untrack() to break effect loop

Svelte 5 $effect tracks every $state read inside its body. The
lifecycle effect that calls game.connect(gameId) implicitly read
state.ws (inside connect()) and then wrote to it, producing an
effect_update_depth_exceeded loop. Symptom in production: the
browser opened ~12 WS connections/sec, none completed the upgrade
handshake, and the lobby flow appeared stuck on 'waiting for
opponent' (the opponent's WS never stabilized long enough for the
server to send 'joined'). untrack() opts the call out of dep tracking.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/client/src/lib/Game.svelte

@@ -1,4 +1,5 @@
 <script lang="ts">
+  import { untrack } from 'svelte';
   import { game } from './stores/game.svelte.js';
   import Board from './Board.svelte';
   import ModeratorPanel from './ModeratorPanel.svelte';
@@ -11,9 +12,14 @@
   let armedSquare: Square | null = $state(null);
   let pendingPromotion: { from: Square; to: Square } | null = $state(null);
 
+  // Lifecycle effect: connect once when gameId becomes known, disconnect on
+  // teardown. untrack() prevents the connect/disconnect call from registering
+  // any state reads as effect dependencies — without it, reading state.ws
+  // inside connect() triggers Svelte's effect_update_depth_exceeded loop.
   $effect(() => {
-    game.connect(gameId);
+    const id = gameId;
-    return () => game.disconnect();
+    untrack(() => game.connect(id));
+    return () => untrack(() => game.disconnect());
   });
 
   // Once the server commits, our local arm clears (visual state slaved to server).