Addresses 8 issues found by dual code review:
- Add readOnly + optionsText to CustomFieldInput type
- Replace computed with mutable ref + refresh() in composable
- Add metadata fallback for fields without customFieldId
- Add onValueCreated callback to keep parent reactive state in sync
- Merge Task 4+5 to avoid type mismatch in intermediate state
- Detail surgical refactoring of transformComponentCustomFields
- Define data contract for ComponentItem/PieceItem (pre-merged)
- Fix hasDisplayableValue to handle readOnly fields
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>