feat!: Update font to Ubuntu Sans

[ashuntu]

Updates the default font from Ubuntu to Ubuntu Sans and Ubuntu Mono to Ubuntu Sans Mono.

This uses the variable fonts from https://github.com/canonical/Ubuntu-Sans-fonts/tree/main/fonts/variable and https://github.com/canonical/Ubuntu-Sans-Mono-fonts/tree/main/fonts/variable.

This requires >=Flutter 3.41 to support FontWeight for variable fonts.

I've also added some toggles/sliders to the font page so you can view different variations of the fonts. Leaving weight and width unchecked will use the default weight and width of the given text style.

	Before	After
Light
Dark

cc @juanruitina

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UDENG-9088

[ashuntu]

@juanruitina can you confirm this looks correct? I believe the new font has some slightly thicker weight.

[juanruitina]

Thank you for all this. Can we move the variable fonts perhaps to a togglable container (perhaps YaruExpansionPanel) below the style examples? I think it's good that the variable fonts can be used, but we should encourage using the default styles first. Other than that, I think it all looks as it should.

[ashuntu]

Since this change is very minor but breaking because of the Flutter upgrade, I think we should consider postponing this for Yaru 11+, especially since Flutter 3.41 is so new.

[Feichtmeier]

Since this change is very minor but breaking because of the Flutter upgrade, I think we should consider postponing this for Yaru 11+, especially since Flutter 3.41 is so new.

alright!

[Muqtxdir]

Hi @ashuntu @Feichtmeier do I close my pr #996 in favour of this?

[ashuntu]

Hi @ashuntu @Feichtmeier do I close my pr #996 in favour of this?

I think this PR has the benefit of utilizing the 3.41 features to apply font weights, however, this obviously requires Flutter 3.41.

I don't necessarily think this is conflicts directly with #996, as we could technically merge #996 if the CI passed and then merge this PR later for the 3.41 weight features. I also haven't tested #996 to see how it interacts with custom weights in code. Ultimately, this is up to @Feichtmeier and others.

[Feichtmeier]

Hi @ashuntu @Feichtmeier do I close my pr #996 in favour of this?

I think this PR has the benefit of utilizing the 3.41 features to apply font weights, however, this obviously requires Flutter 3.41.

I don't necessarily think this is conflicts directly with #996, as we could technically merge #996 if the CI passed and then merge this PR later for the 3.41 weight features. I also haven't tested #996 to see how it interacts with custom weights in code. Ultimately, this is up to @Feichtmeier and others.

sure sounds like a plan, align yaru with 3.41 (but is it stable enough on linux? I became quite conservative with flutter versions in the last year and am rocking 3.38.10 pretty solid on all operating systems) and then merge this here

[ashuntu]

but is it stable enough on linux

Yeah, I think that's why we should keep this as draft for a while, most likely until our Ubuntu apps are up to date which probably won't be for a little while due to previous instability with Flutter upgrades.

[Feichtmeier]

We also need emoji fallback fonts, please @ashuntu if you keep working on this PR again, let's fix emojis and chinese fonts on ARM with this branch here, they are bugged like hell with yaru.dart