Push and install now consume private copies whose stable hashes identify the
transferred bytes. Preserve original caller paths, remote side-effect receipts
and cancellation through final cleanup. Retain failed snapshot owners in the
existing directory cleanup lifecycle and remove redundant stored identity.
Validated path replacement through real subprocess stubs and a public CLI
negative/positive reproduction, plus capacity, cancellation and cleanup retry.
The small cold/warm CLI comparison does not establish a speed improvement.
Real Android devices and Windows private-root behavior were not exercised.
Refs #4252.
morluto
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