0443 — pkg/consumer is a door, not a vocabulary layer

Context. Converting pkg/consumer (4362 lines across 17 files) to the three-layer pattern collided with one non-negotiable symbol: consumer.NewConsumer keeps its name and package, because it is the thing users type.

Decision. pkg/consumer is a DOOR rather than a vocabulary layer. The sorting rule that placed every symbol: nothing a user types may live below the door — the door imports the row packages, and the rows may not import back. Because there is no vocabulary layer, the read-models live in the controller.

Consequences. The package tree was derived mechanically from that one constraint plus the import arrows, not designed fresh. The consumer domain permanently deviates from the standard shape (no pkg/<x> vocabulary layer), a cost accepted to keep the public entry point stable.