Post Serving Teardown

Undeploy an org's live serving adapters (called on org deletion).

Owner-gated: the frontend org-delete flow calls this with the deleting owner's session BEFORE removing the org row, so the live Modal adapters are stopped and the GPU capacity reclaimed (otherwise serving keeps billing after the org is gone, since the db cascade only removes the adapter rows, not the running app). Best-effort per adapter; returns the per-adapter teardown counts.