🎨 Palette: [UX improvement] Add loading spinner to Refresh Data button

[docxology]

💡 What: Added a loading spinner (<span class="loader"></span>) to the "Refresh Data" button when clicked.
🎯 Why: To provide immediate visual feedback that an asynchronous operation is in progress, preventing the user from wondering if the click registered or if the application is hung.
📸 Before/After: The button now displays a spinner next to "Refreshing..." instead of just changing text.
♿ Accessibility: N/A - primarily a visual feedback improvement.

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PR created automatically by Jules for task 16577131920192443041 started by @docxology

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