Derive Darwin subprocess test budgets from the bounded ownership compiler budget while preserving short command deadlines. Always join the retained command scope after test failures.
Refs #5094.
Attempt independent auth and run-tree cleanup even after permission denial,
retaining the primary verification failure alongside cleanup errors. Exercise
both retention modes through the verifier entrypoint, preserve startup
diagnostics, and retain cooperative coverage for root.
Fixes#5095
Assisted-by: Reimu (gensokyo-skills:reimu-incident-triage)