What it does
Answers the case the shortcut leaves alone, a field typed by a CDS enum. @enumValueHelp on the field makes the plugin add @Common.ValueList against a generated EnumValueHelpView that serves the enum's own values by entity and field, and @enumValueHelpFixedValues adds @Common.ValueListWithFixedValues as well, which is what makes the control a dropdown rather than a search dialog. It scans for the annotations while the CDS model loads and exposes the view to the services that hold an annotated entity.
Remaining work
Mark each enum field, and @enumValueHelpFixedValues as well where the list should be fixed. Nothing picks the fields.