Resolves the authenticated requester's email (ADR-0059), resolves + caps the
property selection, pins the recipe (landlord_property_ids, recipient_email,
package_name) onto one pre-created sub_task (raw SQL, dodging the mirror
double-registration), and enqueues one message to the worker. Refuses
double-submits (409) and oversized selections (400).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
