Improve keyboard navigation and accessibility (a11y)

[AditthyaSS]

Several accessibility improvements are needed:

Add aria-selected to recent search dropdown items
Add keyboard navigation (↑/↓ arrow keys) in search dropdown
Add role="search" to the search

Escape key should blur the search input (currently only closes dropdown)
Add visible focus indicators for all interactive elements
Add aria-label to icon-only buttons that are missing them
Ensure color contrast ratios meet WCAG AA for all text

[Payal29037]

Hi! I'd like to work on this issue as part of ECSoC. Could you please assign it to me?