Stage 17 #2: extend the offline soft-disable to all server-action buttons

Following the in-game bar, the Connecting indicator now also visually disables the
other proactive (server-sending) controls while offline: chat send + nudge, profile
save / link email|telegram / merge-confirm, friends (redeem, get-code, accept/decline,
unfriend, block, unblock), New Game (auto-match variant + send-invitation) and the
lobby hide ❌. Purely local controls (board/rack/reset, menus, navigation, settings,
copy-code) stay live. Each reads the global connection.online signal; full e2e + check
green.

ui/src/screens/Lobby.svelte

@@ -4,6 +4,7 @@
   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';
   import { gateway } from '../lib/gateway';
   import { navigate } from '../lib/router.svelte';
   import { t, type MessageKey } from '../lib/i18n/index.svelte';
@@ -191,7 +192,7 @@
             {#each group.list as g (g.id)}
               <div class="rowwrap" class:revealed={group.finished && revealedId === g.id}>
                 {#if group.finished}
-                  <button class="del" onclick={() => hide(g.id)} aria-label={t('lobby.hideGame')}>❌</button>
+                  <button class="del" onclick={() => hide(g.id)} disabled={!connection.online} aria-label={t('lobby.hideGame')}>❌</button>
                 {/if}
                 <div class="row">
                   <button