🎨 Palette: Comprehensive Form & Dropzone Accessibility Improvements

[Nawayisus]

💡 What

• Associated form labels with inputs using the for attribute.
• Upgraded the progress area to be a polite live region with dynamic aria-valuenow updates.
• Empowered the custom drag-and-drop zone with full keyboard and mouse accessibility, avoiding interaction bugs.
• Recorded a critical finding about dropzone event handling in the Palette journal.

🎯 Why

• Screen readers rely on semantic <label for="id"> associations to properly announce form inputs.
• Without aria-live, dynamic progress updates remain invisible to assistive technologies.
• Custom drop zones (built from standard <div> elements) fail keyboard navigation and interaction without explicit roles, tab indexes, and event listeners. The implementation specifically prevents a known issue where clicking an inner button causes a bubbling double-trigger on the hidden file input.

♿ Accessibility

• Full WCAG compliance on form controls, live regions, and custom interactive widgets.

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PR created automatically by Jules for task 13390089907722529709 started by @Nawayisus

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