An empty `vlan=` in a dry run reads like a defect and would hide a real
one. On a from-scratch build the target fabric does not exist yet when the
MOVE and space-bind lines are planned, so their ids cannot resolve; they
now print <vlan-of-NAME> / <fabric-for-PLANE>. Four assertions added.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HvCyrwvYTTcDYnRErfMsNf