NepaliDatePickerDialogViewController
Hosts NepaliDatePickerDialog with a calendar inside it.
The controller renders the dialog immediately and stays transparent behind it, so add it over the app's own content from Swift (a SwiftUI overlay works well) and remove it when onDismiss fires. Do not wrap it in a sheet or a fullScreenCover, which would close out of step with the dialog.
Parameters
date selected when the dialog opens, or null for no selection.
language, date format and digit script the dialog renders with.
first Bikram Sambat year the picker allows.
last Bikram Sambat year the picker allows.
policy deciding which dates are enabled, or null to allow every date.
knobs for the calendar inside the dialog, or null for the defaults.
dialog chrome, or null for the defaults.
receives the content height in points. A dialog is an overlay, so this reports the inline content only and is normally ignored.
invoked with the selection when the confirming button is tapped.
invoked when the dialog is dismissed without confirming.