Allow the runmgr-to-cmdbus edge in the architecture ratchet

Why: Backend #114 (EXT-14, commands-as-tools) added the runmgr -> cmdbus
production import but its Dev-side ratchet update went missing, so make test
fails on any Dev head combining it (backend CI does not run the Dev
architecture check). Recorded here with the merge that surfaces it.

Evidence: SELF - lint-boundaries passes after the entry; the edge exists in
backend main (internal/runmgr/runmgr.go imports cmdbus).

Impact: Ratchet baseline only; unblocks the Dev combination for all in-flight
work.

policy/architecture-baseline.json

@@ -38,6 +38,7 @@
   "backend/route backend/intentgate",
   "backend/runmgr backend/bus",
   "backend/runmgr backend/cardsvc",
+  "backend/runmgr backend/cmdbus",
   "backend/runmgr backend/ingest",
   "backend/runmgr backend/intentgate",
   "backend/runmgr backend/profiles",