The vendor field on the PO forms was a plain native <select>, forcing
users to scroll the full vendor list. Mirror the item-search UX with a
searchable combobox that filters by vendor name and formal code
(vendorId), case-insensitively. The vendor list is already client-side,
so this is a pure in-memory filter — no API or DB change.
New VendorSelect component (components/ui/vendor-select.tsx) is a
self-contained portal-rendered combobox posting a hidden vendorId input,
so it drops into all three PO forms unchanged on the server:
- po/new/new-po-form
- po/[id]/edit/edit-po-form
- approvals/[id]/manager-edit-po-form
Preserves the optional field, "No vendor selected" empty option, and the
"{name} (CODE)" / "(unverified)" label. Unverified vendors (null code)
remain findable by name. Adds unit tests for the filter logic and
component behaviour.
Fixes#109
