fix(cutter): normalize command checkpoint cancellation

Produce typed cancellation at each command checkpoint while retaining the exact opaque reason as cause. Preserve independent typed physical failures without downstream equality guesses.

Validated 72 focused tests across nine files, static checks, docs and five conformance controls, including real client/service admission races and matching physical-error controls. No native Cutter engine or new public-transport reproduction claimed.

Refs: #4635

docs/reverse-engineering-tools.md

@@ -76,6 +76,9 @@ probe retries the original command. Failed acknowledgements remain pending and
 block new commands until they can be retried successfully. Status proof failures
 identify `cutter_command` and retain `status` in
 `details.diagnostics.auxiliary_operation`; malformed proof still blocks dispatch.
+Descriptor failures likewise retain the requesting operation through cleanup.
+Command admission reports typed cancellation and treats the caller's abort reason
+as opaque metadata, without inferring cleanup ownership from it.
 
 ## Configuration and coverage