Stage 7 polish: app shell + nav + lobby + settings (Parts A/B/C)

- Screen.svelte shell: nav bar grows, ad+content+tabbar pinned bottom (mobile feel)
- AdBanner.svelte + banner.ts rotator (params, mock long/short, linkify); Header CSS chevron + grow; Menu (bigger CSS hamburger); TabBar + HoldConfirm shared components; user-select:none
- Lobby: hide-empty sections, tab order New/Tournaments/Stats, place-based result badges (result.ts)
- Settings: Board style > Labels (beginner/classic/none) + prefs plumbing (boardlabels.ts); i18n keys + ru mirror

ui/src/screens/NewGame.svelte

@@ -1,6 +1,6 @@
 <script lang="ts">
   import { onDestroy } from 'svelte';
-  import Header from '../components/Header.svelte';
+  import Screen from '../components/Screen.svelte';
   import { gateway } from '../lib/gateway';
   import { handleError } from '../lib/app.svelte';
   import { navigate } from '../lib/router.svelte';
@@ -31,8 +31,6 @@
         navigate(`/game/${r.game.id}`);
         return;
       }
-      // The match also arrives via the live stream (handled in app), but poll as a
-      // fallback for a client that is not currently streaming.
       poll = setInterval(async () => {
         try {
           const p = await gateway.lobbyPoll();
@@ -53,23 +51,24 @@
   onDestroy(stop);
 </script>
 
-<Header title={t('new.title')} back="/" />
-<main class="page">
-  {#if searching}
-    <div class="searching">
-      <div class="spinner"></div>
-      <p>{t('new.searching')}</p>
-      <button class="cancel" onclick={() => { stop(); navigate('/'); }}>{t('common.cancel')}</button>
-    </div>
-  {:else}
-    <p class="subtitle">{t('new.subtitle')}</p>
-    <div class="variants">
-      {#each variants as v (v.id)}
-        <button class="variant" onclick={() => find(v.id)}>{t(v.label)}</button>
-      {/each}
-    </div>
-  {/if}
-</main>
+<Screen title={t('new.title')} back="/">
+  <div class="page">
+    {#if searching}
+      <div class="searching">
+        <div class="spinner"></div>
+        <p>{t('new.searching')}</p>
+        <button class="cancel" onclick={() => { stop(); navigate('/'); }}>{t('common.cancel')}</button>
+      </div>
+    {:else}
+      <p class="subtitle">{t('new.subtitle')}</p>
+      <div class="variants">
+        {#each variants as v (v.id)}
+          <button class="variant" onclick={() => find(v.id)}>{t(v.label)}</button>
+        {/each}
+      </div>
+    {/if}
+  </div>
+</Screen>
 
 <style>
   .page {
@@ -92,6 +91,7 @@
     border-radius: var(--radius);
     font-size: 1.05rem;
     font-weight: 600;
+    user-select: none;
   }
   .searching {
     display: grid;