🎨 Palette: Enhance accessibility for common interactive elements

[Woschj]

This PR implements several micro-UX and accessibility improvements across the application's core templates.

Key changes:

• QuickScan Modal: Added role="button", tabindex="0", and onkeydown handlers to the "Item" and "Worker" cards, making them fully keyboard-accessible as per project standards.
• List Views: Enhanced the search bar and filter selects with descriptive aria-label attributes (Suchen, Kategorie filtern, etc.) to provide context for screen reader users.
• Navbar: Added an aria-label to the department switch button to ensure its purpose is clear even when its text label is hidden on mobile devices.
• Icons: Applied aria-hidden="true" to decorative icons inside buttons to reduce redundant screen reader announcements.

These changes ensure that critical interactive paths in Scandy are more inclusive and accessible while maintaining the existing visual design.

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PR created automatically by Jules for task 2621348759778649125 started by @Woschj

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