UI: gesture & history polish — pinch/swipe fix, wider back-swipe, nudge align, history overscroll

- Stop a two-finger pinch-out from also opening the history: the board wrapper arms its
  open/close pull only while a single pointer is down (a 2nd finger is a pinch, owned by Board).
- Widen the edge-swipe-back activation band to the left half of the viewport (was 20%).
- Align a chat nudge by sender like a bubble — your own to the right, the opponent's to the
  left (only the alignment changes).
- Kill the iOS rubber-band inside the history drawer (overscroll-behavior: none).

e2e: a two-finger pinch does not open the history; a back-swipe from the left half navigates back.

ui/e2e/edgeswipe.spec.ts

@@ -40,6 +40,17 @@ test('a rightward swipe in the left band returns to the lobby', async ({ page })
   await expect(page.getByRole('button', { name: /Ann/ })).toBeVisible();
 });
 
+test('a rightward swipe from the left half (past the old edge band) returns to the lobby', async ({ page }) => {
+  await openAnnGame(page);
+  const board = (await page.locator('.viewport').boundingBox())!;
+
+  // ~38% of the 390px viewport: inside the new half-width band, outside the old 20% edge band.
+  await touchDrag(page, 150, board.y + board.height * 0.5, 320, board.y + board.height * 0.5);
+
+  await expect(page).toHaveURL(/#\/$/);
+  await expect(page.getByRole('button', { name: /Ann/ })).toBeVisible();
+});
+
 test('a swipe starting on the rack does not navigate (hit-test guard)', async ({ page }) => {
   await openAnnGame(page);
   const rack = (await page.locator('[data-rack]').boundingBox())!;