helium/ui/centered-address-bar: add centered address bar

[jamdaniels]

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  (an approved feature request, or confirmed bug).
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Tested on (check one or more):

• Windows
• macOS
• Linux

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This PR adds a setting to toggle between the current used, full width address bar and a more narrow, centered, responsive address bar with a fixed max width of 900px. Currently, the full-width address bar is disabled by default. These additions are skipped if the CAT feature is active. I've researched how the centered, responsive address bar is implemented in Brave, which already does this and this solution is inspired by it.

Closes #104

Pictures:

Video showcase:

helium-wide-address-bar.mp4

I do want to say that I used AI to implement this, but I didn't "vibe code" it. I did a lot of back and forth with multiple frontier models, discussed how to implement this feature properly while following best practices and look out for possible concerns and thoroughly tested all scenarios locally. I just want to help out and I would love if this feature gets added. If the full-width address bar should stay the default, let me know and I'm happy to change that and anything else necessary.

[wukko]

the full width address bar should indeed stay default & please use dev.sh, it sets the correct env variables for quilt that make the patches look better

[jamdaniels]

• changed approach to 'enable centered address bar'
• added hunk offset fixes

I hope this fits better, I also tried to match the naming patterns.

helium-pr-1.mp4