Add keyboard navigation tests for Select and Combobox

[theg1239]

Summary

• Select and Combobox in apps/desktop/src/components/ui/Select.tsx implement detailed keyboard support but lack automated tests.
• Add Vitest + Testing Library coverage to lock in the expected behaviour.

Why it matters

• Accessibility regressions are easy to miss without tests; this ensures arrow keys, Enter, Escape, and focus traps keep working.

Acceptance Criteria

• Create tests under apps/desktop/src/tests/ that render Select and Combobox and assert keyboard interaction flows (open/close, cycling options, escape to trigger).
• Verify disabled options are skipped when navigating with Arrow Up/Down.
• Ensure the Combobox test covers searching and committing a custom entry.

Additional context

• Existing tests (e.g., OpenWithDialog.test.tsx) show how the test harness is configured.

[Maitri-shah29]

I would like to work on this..