🎨 Palette: Use semantic fieldsets for grouping form controls

[n24q02m]

💡 What: Replaced generic <div> tags that used explicit role="group" / role="radiogroup" and aria-labelledby attributes with native semantic HTML <fieldset> and <legend> tags in the popup.
🎯 Why: To improve the underlying markup and adhere to the W3C recommended standard for grouping related form controls (like radio buttons). This improves the experience for screen reader users natively.
📸 Before/After: Visuals are exactly the same, as the browser default styling for <fieldset> was reset.
♿ Accessibility: Uses the native semantic <fieldset> and <legend> elements rather than explicit ARIA attributes, providing a more robust accessible experience out of the box.

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PR created automatically by Jules for task 8600619215105986868 started by @n24q02m

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[github-actions]

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