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/screens/Lobby.svelte

@@ -1,7 +1,6 @@
 <script lang="ts">
   import { onMount } from 'svelte';
   import Screen from '../components/Screen.svelte';
-  import Menu from '../components/Menu.svelte';
   import TabBar from '../components/TabBar.svelte';
   import { app, handleError, showToast } from '../lib/app.svelte';
   import { connection } from '../lib/connection.svelte';
@@ -24,7 +23,9 @@
       games = (await gateway.gamesList()).games;
       if (!guest) {
         [invitations, incoming] = await Promise.all([gateway.invitationsList(), gateway.friendsIncoming()]);
-        app.notifications = invitations.length + incoming.length;
+        // The ⚙️ badge counts only what lives behind it (incoming friend requests);
+        // invitations surface in their own lobby section above.
+        app.notifications = incoming.length;
       }
       setLobby({ games, invitations, incoming });
     } catch (e) {
@@ -116,13 +117,6 @@
     }
   }
 
-  const menuItems = $derived([
-    ...(guest ? [] : [{ label: t('lobby.friends'), onclick: () => navigate('/friends'), badge: incoming.length }]),
-    { label: t('lobby.profile'), onclick: () => navigate('/profile') },
-    { label: t('lobby.settings'), onclick: () => navigate('/settings') },
-    { label: t('lobby.about'), onclick: () => navigate('/about') },
-  ]);
-
   async function acceptInvite(inv: Invitation) {
     try {
       const r = await gateway.invitationAccept(inv.id);
@@ -151,10 +145,6 @@
 </script>
 
 <Screen title={app.profile?.displayName ?? t('app.title')}>
-  {#snippet menu()}
-    <Menu items={menuItems} badge={app.notifications} />
-  {/snippet}
-
   <div class="lobby">
     {#if invitations.length}
       <section>
@@ -238,6 +228,10 @@
       <button class="tab" onclick={() => showToast(t('lobby.soon'))}>
         <span class="sq">🏆</span><span class="lbl">{t('lobby.tournaments')}</span>
       </button>
+      <button class="tab" onclick={() => navigate('/settings')}>
+        <span class="sq">⚙️{#if app.notifications > 0}<span class="badge">{app.notifications}</span>{/if}</span>
+        <span class="lbl">{t('lobby.settings')}</span>
+      </button>
     </TabBar>
   {/snippet}
 </Screen>