feat(newgame): skip the take-a-seat prompt for a guest offline host

A guest host has no meaningful display name to seat, so the offline 'with friends' flow's
"do you take a seat?" prompt only produced a nameless seat. For a guest the prompt is skipped:
after the master PIN, the two empty player seats show directly. A durable host is still asked.

ui/e2e/native.spec.ts

@@ -97,14 +97,15 @@ test.describe('native offline-first', () => {
     await expectOfflineGuestLobby(page);
 
     // New game -> the offline mode selector offers "with friends" (pass-and-play) to the local guest.
-    // A minimal create: set the mandatory host (master) PIN, decline a seat, the sole offered variant
+    // A minimal create: set the mandatory host (master) PIN. A guest host skips the "do you take a
-    // (Erudit — the profileless guest's default), two open seats.
+    // seat?" prompt (no name to seat) and goes straight to the two open seats, so pick the sole
+    // offered variant (Erudit — the profileless guest's default) right after the PIN.
     await page.locator('button.tab').nth(0).click();
     await page.getByRole('button', { name: /With friends|друзьями/i }).click();
     await page.locator('.hostpin .plink').click();
     await typePin(page, '9999');
     await typePin(page, '9999');
-    await page.getByRole('button', { name: /^(No|Нет)$/ }).click();
+    await expect(page.getByRole('button', { name: /^(No|Нет)$/ })).toHaveCount(0); // no seat prompt for a guest
     await page.locator('.variant').click();
     await page.locator('.pname').nth(0).fill('Ann');
     await page.locator('.pname').nth(1).fill('Bob');

ui/src/screens/NewGame.svelte

@@ -265,7 +265,10 @@
       case 'host-set':
         if (r.kind === 'set') {
           hostPin = r.lock;
-          askHostPlays = true;
+          // A guest host has no meaningful display name to seat, so the "do you take a seat?"
+          // prompt would only produce a nameless seat — skip it and go straight to the (empty)
+          // player seats. A durable host is still asked.
+          if (!guest) askHostPlays = true;
         }
         break;
       case 'host-change':