Add escrow.Consume(blob, R, expectedFingerprint, keyDest): Unwrap -> fingerprint
gate -> atomic 0600 install. Bakes in the spike findings — wrong R fails closed
(no write), the fingerprint gate runs BEFORE any restore (no install on
mismatch), the input blob is read-only (retryable), K is never mutated, R/key
bytes never logged. Zero-knowledge holds: the hub serves all but R (by hand).
--selftest=escrow-consume invokes the real path live. Agent-only; no hub change.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
