Stage 17 round 6 (cluster 1): profile, tap flash, variant naming, chat/nudge by turn

- Profile: drop the hint-balance line.
- Board: no mobile tap flash on a cell tap (-webkit-tap-highlight-color: transparent),
  matching the web click; the only intentional cell animation stays the last-word flash.
- Variant names keyed by the game's alphabet, not the UI language: english -> Scrabble
  always, russian_scrabble -> Скрэббл always (unlocalized, never collide), erudit localized.
- Chat/nudge are mutually exclusive by turn: the message field + Send show on your turn,
  the nudge replaces them on the opponent's turn; while the nudge cooldown is active the
  button is disabled with a grey 'awaiting reply' caption to its left.

ui/e2e/social.spec.ts

@@ -165,12 +165,14 @@ test('link account: the Telegram web sign-in control is offered in a browser', a
   await expect(page.getByRole('button', { name: 'Link Telegram' })).toBeVisible();
 });
 
-test('chat send and nudge are icon buttons', async ({ page }) => {
+test('chat: the message field shows on your turn, the nudge replaces it otherwise', async ({ page }) => {
   await loginLobby(page);
-  await page.getByRole('button', { name: /Ann/ }).click();
+  await page.getByRole('button', { name: /Ann/ }).click(); // g1: your turn
   await page.locator('.burger').first().click();
   await page.getByRole('button', { name: 'Chat' }).click();
-  // Icon-only controls expose their action through the aria-label.
+  // On your turn the message field + Send are shown and the nudge is hidden (Stage 17);
+  // chat and nudge are mutually exclusive by turn. Icon-only controls expose their action
+  // through the aria-label.
   await expect(page.getByRole('button', { name: 'Send' })).toBeVisible();
-  await expect(page.getByRole('button', { name: 'Nudge' })).toBeVisible();
+  await expect(page.getByRole('button', { name: 'Nudge' })).toHaveCount(0);
 });