Disable zoom on custom pages

[tfuxu]

Instead of globally storing zoom level, it should be stored by each webview page (and it should be disabled completely in custom pages, eg. input page)

We should disable zoom controls on custom pages (eg. user input page), as they can't be (easily, if at all) resized.

[ranfdev]

I'm ok with disabling the zoom on the custom pages, like the input one, but it doesn't make much sense to have a separate zoom for each gemini page.

HTML browsers have different zoom levels for each page because each website has a custom font size. Here the font size is the same everywhere. Why would a user zoom page X but not page Y when the formatting is the same?

[tfuxu]

I agree, I've updated title and issue description to focus it only on disabling zoom in custom pages.