Astra: relocation round 8

Round 7 (CODEX-REVIEW-L18-MERGE-7.md) raised one P2: a replaced target's new install stamp failed the prepared-authority stamp check. Two commits since:

• 15ffddfa, the round-7 fix. - The install journal's files_manifest step now records P's build stamp, the one prepared_authority binds, alongside key, op, digest and exact version. The install reads the prepared authority to get it, and refuses one with no build stamp, or a manifest whose digest isn't the authority's. - The reader checks the step against prepared_authority exactly. It checks the holder's stamp, this box's local_install receipt and its install journal against the current install stamp. It also requires build stamp < install stamp. - Tests cover replacement at installed, and in probing before P's first admission, through the real provider. Each failed on the old code. They also cover refusing a stale install journal from the replaced box, and refusing an authority stamp at or past the install stamp. A mutation check (step checked against the install stamp) kills both positives.
• a9610787, a CI fix. On 03212a8b, internal/release TestVerifyHeldLiveUnderReadsUnderTheClaim asserted that VerifyHeldLive refuses under CARLOS_HOST_CLAIM. Main (moves-phase1-5f, Paul's T7 ruling) made VerifyHeldLive read under the claim, because it writes nothing. The test now asserts that it passes. No relocation code calls VerifyHeldLive.

Open question the builder raised; please trace it. When a target is replaced at installed, what activates the replacement box's install guard at the new stamp? The builder found the guard activated only during the build, while the install refuses any other stamp. The test activates it directly. Main's reconciler may cover it, but the builder didn't trace that. Is this a real gap, meaning a replacement at installed never progresses or progresses unguarded? Or is it covered, and where? Check hostclaim/relocation.go around the replacement transition, relocation's install and build paths, and the guard activation sites.

Judge:

1. Is round 7's P2 closed?
2. The guard-activation question above.
3. Anything new in these two diffs?
4. Verdict: may relocation merge dormant?

Give findings P1/P2/P3 with file:line. Report only new items.