fix(hint): arm the vs_ai idle-gate from the warm cache so the lock shows without a delay

Entering a vs_ai game from the lobby armed the idle-hint countdown only in load() (after
the gameState round-trip), so the lock popped in after a visible delay. Arm it on the
instant warm-cache render in onMount too — the preloadGames-warmed StateView carries
hint_unlock_left_seconds; load() then refreshes the snapshot. A first move (0 seconds
left) stays open.

ui/src/game/Game.svelte

@@ -290,6 +290,9 @@
     if (cached) {
       view = cached.view;
       moves = cached.moves;
+      // Arm the vs_ai idle-hint countdown from the cached seconds-left so the 🔒 shows at once on a
+      // warm open (no wait for load()); the cached value is a snapshot, refreshed by load() below.
+      armHintGate(cached.view.game.vsAi ? (cached.view.hintUnlockLeftSeconds ?? 0) : 0);
       // Apply the cached draft synchronously so a warm/preloaded open paints the pending tiles
       // already on the board (no full-rack-then-jump). load() then refreshes in the background.
       applyDraft(cached.view, cached.draft ?? '');