Copy one event type from a source EarthRanger site to a destination site.
For v2 event types, the choice option-sets the schema references are copied
too. The target event category must already exist on the destination.
v2: reads the source event type's schema, extracts every
choices.json?field=...$ref, copies those Choice records to the
destination, then creates the event type attached to
--target-event-category.
v1: copies the event type with its inline schema as-is.
Honors the global --dry-run flag — reads from the source, logs the
writes it would send to the destination.