🎨 Palette: Add aria-expanded and keyboard navigation to accordion panels

[d3mocide]

💡 What: Added missing aria-expanded attributes to expandable sections in JS8Widget.tsx and AIAnalystPanel.tsx. In JS8Widget.tsx, enhanced the div-based accordion header with role="button", tabIndex={0}, keyboard support (onKeyDown), and focus styles.

🎯 Why: To ensure screen readers accurately announce the state of expandable elements (open or closed) and allow keyboard navigators to operate accordion headers properly.

♿ Accessibility:

• Added aria-expanded to settings toggle in AIAnalystPanel.
• Upgraded the header div in JS8Widget to act as an accessible button, providing full keyboard accessibility with explicit Enter/Space support and a visible focus ring.

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PR created automatically by Jules for task 13937038800600848916 started by @d3mocide

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