UI: tab-bar navigation — drop the hamburger

Replace Menu.svelte (hamburger) everywhere with tab-bar navigation:
- Settings hub (SettingsHub) from the lobby ⚙️ tab: Settings/Profile/
  Friends/About as in-place tabs, back → lobby; the lobby ⚙️ badge counts
  incoming friend requests (invitations keep their own lobby section).
- Comms hub (CommsHub) from the move-history 💬: Chat/Dictionary tabs,
  back → game; Dictionary only while the game is active.
- Game menu items relocate into the open history: 🏁 leave / 📤 export in
  the header, 🤝 add-friend per opponent card, 💬 comms; unread chat is
  badged on the score bar + the 💬.
- TapConfirm (tap → fading ✅ → tap) replaces the Skip/Hint press-and-hold
  popovers and drives the add-friend confirm.
- Fix the move-history "jump": the slid board is inert and the stage can't
  scroll, so a swipe up genuinely closes the history.

Remove Menu.svelte + HoldConfirm.svelte. Docs: UI_DESIGN, FUNCTIONAL(+ru),
PRERELEASE. UI check/unit/build/bundle/e2e (Chromium+WebKit) all green.

ui/src/game/CheckScreen.svelte

@@ -1,6 +1,5 @@
 <script lang="ts">
   import { onMount } from 'svelte';
-  import Screen from '../components/Screen.svelte';
   import { gateway } from '../lib/gateway';
   import { handleError, showToast } from '../lib/app.svelte';
   import { t } from '../lib/i18n/index.svelte';
@@ -60,27 +59,25 @@
   }
 </script>
 
-<Screen title={t('game.checkWord')} back={`/game/${id}`}>
-  <div class="wrap">
-    <div class="check">
-      <input
-        value={word}
-        oninput={onInput}
-        onkeydown={(e) => e.key === 'Enter' && runCheck()}
-        placeholder={t('game.checkWordPrompt')}
-      />
-      <button onclick={runCheck} disabled={!canCheck()}>{t('game.check')}</button>
-    </div>
-    {#if result}
-      <p class="verdict" class:ok={result.legal} class:bad={!result.legal}>
-        {result.legal
-          ? t('game.wordLegal', { word: result.word })
-          : t('game.wordIllegal', { word: result.word })}
-      </p>
-      <button class="complain" onclick={complain}>{t('game.complain')}</button>
-    {/if}
+<div class="wrap">
+  <div class="check">
+    <input
+      value={word}
+      oninput={onInput}
+      onkeydown={(e) => e.key === 'Enter' && runCheck()}
+      placeholder={t('game.checkWordPrompt')}
+    />
+    <button onclick={runCheck} disabled={!canCheck()}>{t('game.check')}</button>
   </div>
-</Screen>
+  {#if result}
+    <p class="verdict" class:ok={result.legal} class:bad={!result.legal}>
+      {result.legal
+        ? t('game.wordLegal', { word: result.word })
+        : t('game.wordIllegal', { word: result.word })}
+    </p>
+    <button class="complain" onclick={complain}>{t('game.complain')}</button>
+  {/if}
+</div>
 
 <style>
   .wrap {