🎨 Palette: [Accessibility] Add semantic Role to MinimalButton

[LeanBitLab]

💡 What: Added semantic Role.Button to the MinimalButton component.
🎯 Why: Screen readers (like TalkBack) were not announcing this clickable layout as a button. This prevents visually impaired users from easily understanding they can interact with the element.
📸 Before/After: Not a visual change.
♿ Accessibility: Improved screen reader announcements for the MinimalButton component.

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PR created automatically by Jules for task 3001398352490313184 started by @LeanBitLab

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