@spec commerce_summary(
  Crosswake.Manifest.Types.Root.t() | nil,
  keyword()
) :: map()

Builds the typed commerce summary surface published alongside the findings stream.

Returns a map with :corridors, :prerequisites, :snapshot_freshness, :proof_posture, and :rebuild_requirements keys derived from the compiled manifest and canonical support matrix entries. Use the :entitlement_snapshot_freshness option (one of :fresh, :stale, :unknown, :not_applicable) to communicate the host-side freshness posture; the default is :not_applicable when no commerce routes are declared and :unknown otherwise.