fix(VWindow): prevent swipe navigation when scrolling a child element - #23075

Description

When a VWindow contains a horizontally scrollable child element (such as a VBtnToggle or VSlideGroup), swiping to scroll the child also triggers the VWindow's swipe gesture, causing an unintended window navigation.

Reproduction

1. Create a VWindow with a VBtnToggle inside (or any horizontally scrollable element)
2. On mobile, swipe horizontally on the scrollable child
3. The VWindow navigates to the next/previous item instead of scrolling the child

Fix

This fix detects whether the touch gesture started inside a scrollable child element. If the child element was scrolled during the gesture, the VWindow swipe is suppressed, allowing the child to handle the scroll naturally.

References

• Fixes [Bug Report][3.9.4] chipgroup in window, slide chips cause toggle window item on mobile #21888
• Related: [Bug Report][3.3.21] v-tabs toggle auto-scroll to top #18447 (previous VWindow scroll fix)

Testing

• On desktop: VWindow navigation via arrows and swipe still works as expected
• On mobile: scrolling a horizontally scrollable child inside a VWindow no longer triggers window navigation
• The fix only applies when the touch target is inside a scrollable element that actually scrolls