Bottom sheet molecule - a CngxDialog positioned at the viewport bottom
with swipe-to-dismiss support.
Place on the same <dialog> element alongside cngxDialog. Adds the
cngx-bottom-sheet CSS class (styled by bottom-sheet-theme.scss).
When CngxSwipeDismiss is also present, auto-wires the swipe output
to dialogRef.dismiss() - no manual (swiped) binding needed.