get-page-dimensions
Get the page width and height from the slide configuration.
Returns a tuple (width, height). If the page has explicit width/height
keys those are used directly; otherwise dimensions are derived from the
paper key. The built-in Typst presentation paper sizes
("presentation-16-9" and "presentation-4-3") are recognised; for any
other paper name the 16-9 default dimensions (841.89pt × 473.56pt) are used
as a fallback.
Parameters
self : dictionary
The current slide self dictionary.
Returns: array