feat(ui): batch of UI polish tweaks

- admin dashboard "Users" count excludes robots (CountUsers, humans only)
- lobby finished-game delete reveal: background matches header/tab-bar (--bg-elev)
- mobile: swipe up on the zoom-out board (no staged tiles) shuffles the rack
- lobby: status icons -25%, game-row top/bottom padding halved
- toast: info tier drifts up ~a tab-bar height while fading over 2s and dismisses
  on tap; error tier unchanged
- game: confirm-move button stays pinned at the right edge; rack tiles shrink to
  fit so a full rack never overflows onto it
- telegram: a successful invite-link redeem shows a welcome window pointing at the bot
- settings: remove the grid-lines toggle; the board is always a gapless checkerboard
- settings/comms hubs: the selected tab highlight wraps icon + label as a pill

Docs: UI_DESIGN (toast, board surface, selected tab), PLAN; e2e updated for the
removed grid-lines toggle.

ui/src/game/CommsHub.svelte

@@ -39,11 +39,11 @@
   {#snippet tabbar()}
     <TabBar>
       <button class="tab" class:active={tab === 'chat'} onclick={() => (tab = 'chat')}>
-        <span class="sq" aria-hidden="true">💬</span><span class="lbl">{t('game.chat')}</span>
+        <span class="face"><span class="sq" aria-hidden="true">💬</span><span class="lbl">{t('game.chat')}</span></span>
       </button>
       {#if active}
         <button class="tab" class:active={tab === 'dictionary'} onclick={() => (tab = 'dictionary')}>
-          <span class="sq" aria-hidden="true">🔎</span><span class="lbl">{t('game.dictionary')}</span>
+          <span class="face"><span class="sq" aria-hidden="true">🔎</span><span class="lbl">{t('game.dictionary')}</span></span>
         </button>
       {/if}
     </TabBar>