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/components/WelcomeRedeemModal.svelte

@@ -0,0 +1,58 @@
+<script lang="ts">
+  import { app, dismissWelcomeRedeem } from '../lib/app.svelte';
+  import { t } from '../lib/i18n/index.svelte';
+  import { botUsername } from '../lib/deeplink';
+  import { telegramOpenLink } from '../lib/telegram';
+  import Modal from './Modal.svelte';
+
+  // Point at the bot the player signed in through (its service language), falling back to the
+  // interface locale, so an ru player is sent to the ru bot and an en player to the en one.
+  const username = $derived(botUsername(app.session?.serviceLanguage || app.locale));
+  // Greet the arriving player by their own display name.
+  const name = $derived(app.profile?.displayName || app.session?.displayName || '');
+  // Interpolate the name, then split the rest around the {bot} token so the bot handle renders
+  // as an inline link (the {name} value is substituted first; {bot} is left for the split).
+  const parts = $derived(t('friends.welcomeRedeem', { name }).split('{bot}'));
+
+  function openBot() {
+    if (username) {
+      const url = `https://t.me/${username}`;
+      // Inside Telegram, openTelegramLink navigates to the bot chat natively; elsewhere fall
+      // back to a new tab.
+      if (!telegramOpenLink(url) && typeof window !== 'undefined') window.open(url, '_blank');
+    }
+    dismissWelcomeRedeem();
+  }
+</script>
+
+{#if app.welcomeRedeem}
+  <Modal title={t('friends.welcomeRedeemTitle')} onclose={dismissWelcomeRedeem}>
+    <p class="msg">{parts[0]}{#if username}<button type="button" class="bot" onclick={openBot}>@{username}</button>{/if}{parts[1] ?? ''}</p>
+    <button class="ok" onclick={dismissWelcomeRedeem}>{t('common.ok')}</button>
+  </Modal>
+{/if}
+
+<style>
+  .msg {
+    margin: 0 0 16px;
+    line-height: 1.5;
+    /* The greeting and the bot sentence are separated by a blank line in the message. */
+    white-space: pre-line;
+  }
+  .bot {
+    background: none;
+    border: none;
+    padding: 0;
+    font: inherit;
+    color: var(--accent);
+    cursor: pointer;
+  }
+  .ok {
+    width: 100%;
+    padding: 10px 12px;
+    border: 1px solid var(--accent);
+    background: var(--accent);
+    color: var(--accent-text);
+    border-radius: var(--radius-sm);
+  }
+</style>