Typst: change default value of page-numbering

[xx02al]

The current implementation of page-numbering defaults to the hard-coded value "1".

I would argue page-numbering should default to none (or false if Quarto uses boolean values only). This allows us to use Typst's page() function with the default numbering: none without explicitly setting page-numbering: none. What actually happens is that Quarto displays a page number. Thus, if Quarto were to default to none(false), (IMO) extension code would be cleaner and more transparent.

Quarto's own templates illustrate this. Take the letter as an example. It has set page(paper: "us-letter", margin: (top: 2cm)) suggesting an intent to use the default numbering: none but instead, Quarto's default page-numbering: true takes over and displays a page number. This intent is supported by the .png shown. (I am aware that it was generated with a Quarto version that did not have the page-numbering option, but it still illustrates the point). As said, we would need to explicitly set numbering: none in the template to achieve the intended result, which is not ideal.

Initial comment: #13515 (comment)