fix(feedback): show the operator reply only on the player's latest message

A reply was bound to 'the latest message that has a reply', so after the player
read a reply and sent a new (unanswered) message, the old reply kept showing as
'Ответ на ваше последнее сообщение'. Bind it to the single most-recent message
instead: sending any new message immediately drops the previous reply (the new
message has no reply yet), well before the one-week window. Client clears the
reply optimistically on submit; the mock mirrors it; inttest covers the case.

ui/e2e/feedback.spec.ts

@@ -45,3 +45,16 @@ test('feedback: an operator reply raises the badge and shows on the screen', asy
   await expect(page.getByText('Reply to your last message')).toBeVisible();
   await expect(page.getByText(/looking into it/)).toBeVisible();
 });
+
+test('feedback: sending a new message clears the previous reply', async ({ page }) => {
+  await loginLobby(page);
+  await page.evaluate(() => (window as unknown as { __mock: { adminReply(): void } }).__mock.adminReply());
+  await openFeedback(page);
+  await expect(page.getByText('Reply to your last message')).toBeVisible();
+
+  // A new message has no reply yet, so the previous reply must stop showing at once.
+  await page.locator('textarea').fill('a follow-up question');
+  await page.getByRole('button', { name: 'Send', exact: true }).click();
+  await expect(page.getByText('Your message has been sent.')).toBeVisible();
+  await expect(page.getByText('Reply to your last message')).toBeHidden();
+});