Replace the free-text Project Code input with a native <select> carrying a
fixed list of project codes (Petronet LNG Cochin, COMACOE Trombay, Haldia
Reach, Haldia MMT, COMACOE Mandvi) plus an empty "— none —" option, across
all three PO forms (new / edit / manager-edit).
- Add a shared PROJECT_CODES constant in lib/validations/po.ts as the single
source of truth.
- Add a reusable <ProjectCodeField> (mirrors <DeliveryLocationField>): plain
HTML select keeping name="projectCode" so the server actions are unchanged.
- The field stays optional; projectCode remains a nullable free-text snapshot
(no schema/migration, no validation tightening) so legacy/imported values
are not rejected. On edit, a current value not in the list is preserved as a
leading "(current)" option so it is never silently dropped.
- Add unit tests for the new field.
Fixes#124
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
