fix: fall back to other axis when main scroll direction is not scrollable

[es27]

Problem

On mobile devices, vertical scrolling inside modals/dialogs is blocked
when the user's finger moves with a slight horizontal offset during a swipe.

shouldCancelEvent in SideEffect.tsx determines moveDirection from
the initial touch delta:

const moveDirection = Math.abs(deltaX) > Math.abs(deltaY) ? 'h' : 'v';

When the horizontal component is even marginally larger, moveDirection
is 'h'. Then locationCouldBeScrolled('h', target) finds no
horizontally scrollable ancestor and the function returns true
(cancel), calling preventDefault() on the touch event. This kills
the vertical scroll.

This is easily reproducible on the Radix UI docs page itself
(radix-ui.com/primitives/docs/components/dialog) — open a Dialog
on a real mobile device and try scrolling with a natural (slightly
diagonal) swipe.

Fix

Before returning true (block), check if the other axis is
scrollable. If it is, switch currentAxis to that axis and continue
with normal scroll handling instead of blocking.

if (!canBeScrolledInMainDirection) {
  const otherAxis = moveDirection === 'v' ? 'h' : 'v';
  if (locationCouldBeScrolled(otherAxis, target)) {
    currentAxis = otherAxis;
    canBeScrolledInMainDirection = true;
  } else {
    return true;
  }
}