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/history.spec.ts

@@ -58,6 +58,46 @@ test('the history is a per-seat grid with move scores but no names or running to
   await expect(grid).not.toContainText('Ann');
 });
 
+test('a two-finger pinch does not open the history (pinch-zoom vs swipe-down)', async ({ page }) => {
+  await openGame(page);
+  await page.locator('.stage').evaluate((el) => (el.scrollTop = 0));
+  const box = (await page.locator('.boardwrap').boundingBox())!;
+  const cx = box.x + box.width / 2;
+  const y0 = box.y + 40;
+
+  // Two fingers land, then spread apart while their centroid drifts down — a pinch-out whose
+  // downward component used to also slide the history open. With the single-pointer guard the
+  // second finger disarms the pull, so the history stays closed.
+  await page.locator('.boardwrap').evaluate(
+    (el, { cx, y0 }) => {
+      const fire = (type: string, id: number, x: number, y: number) =>
+        el.dispatchEvent(
+          new PointerEvent(type, {
+            pointerType: 'touch',
+            pointerId: id,
+            isPrimary: id === 1,
+            clientX: x,
+            clientY: y,
+            bubbles: true,
+            cancelable: true,
+          }),
+        );
+      fire('pointerdown', 1, cx - 20, y0);
+      fire('pointerdown', 2, cx + 20, y0);
+      for (let i = 1; i <= 8; i++) {
+        const d = i * 18;
+        fire('pointermove', 1, cx - 20 - d, y0 + d);
+        fire('pointermove', 2, cx + 20 + d, y0 + d);
+      }
+      fire('pointerup', 1, cx - 164, y0 + 144);
+      fire('pointerup', 2, cx + 164, y0 + 144);
+    },
+    { cx, y0 },
+  );
+
+  await expect(page.locator('.history')).toHaveCount(0);
+});
+
 test('a swipe-down on the zoomed-in board does not open the history (native scroll wins)', async ({ page }) => {
   await openGame(page);
   // Double-tap an empty cell to zoom in (two synchronous clicks = a double-tap).