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/components/AdBanner.svelte

@@ -0,0 +1,77 @@
+<script lang="ts">
+  import { onDestroy, onMount } from 'svelte';
+  import { fade } from 'svelte/transition';
+  import {
+    createBannerRotator,
+    defaultBannerConfig,
+    linkify,
+    mockBanners,
+    type BannerConfig,
+    type BannerItem,
+  } from '../lib/banner';
+
+  let { items = mockBanners(), config = defaultBannerConfig }: { items?: BannerItem[]; config?: BannerConfig } =
+    $props();
+
+  let current = $state(0);
+  let tx = $state(0);
+  let txDur = $state(0);
+  let track = $state<HTMLElement>();
+  let viewport = $state<HTMLElement>();
+
+  let rotator: ReturnType<typeof createBannerRotator> | null = null;
+
+  onMount(() => {
+    rotator = createBannerRotator(items, {
+      overflowPx: () => Math.max(0, (track?.scrollWidth ?? 0) - (viewport?.clientWidth ?? 0)),
+      show: (i) => {
+        current = i;
+        tx = 0;
+        txDur = 0;
+      },
+      scrollTo: (toPx, durationMs) => {
+        txDur = durationMs;
+        tx = -toPx;
+      },
+    }, config);
+    rotator.start();
+  });
+  onDestroy(() => rotator?.stop());
+</script>
+
+<div class="ad" bind:this={viewport}>
+  {#key current}
+    <div
+      class="track"
+      bind:this={track}
+      in:fade={{ duration: config.fadeMs }}
+      style="transform:translateX({tx}px); transition:transform {txDur}ms linear"
+    >
+      {@html linkify(items[current]?.md ?? '')}
+    </div>
+  {/key}
+</div>
+
+<style>
+  .ad {
+    overflow: hidden;
+    white-space: nowrap;
+    padding: 6px var(--pad);
+    background: var(--surface-2);
+    color: var(--text-muted);
+    font-size: 0.85rem;
+    line-height: 1.2;
+    box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.18);
+    border-top: 1px solid var(--border);
+    border-bottom: 1px solid var(--border);
+    user-select: none;
+  }
+  .track {
+    display: inline-block;
+    will-change: transform;
+  }
+  .track :global(a) {
+    color: var(--accent);
+    text-decoration: underline;
+  }
+</style>