Replace the picker with an accessible combobox (role=combobox + role=listbox):
focusing shows the full zone list (no typing/erasing needed), typing filters it
case-insensitively (underscores ignored, so "york" matches America/New_York),
with arrow-key navigation, Enter/click to select, and Escape to close. Fixes the
datalist limitation where a pre-filled value collapsed the dropdown to one match.
e2e updated to type+click options and a type-to-search case added.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
