fix(disconnected): close #997 acceptance containment gaps

[tcconnally]

Summary

• Closes the disconnected-acceptance containment gaps for test(deployment): prove disconnected Perseus + Vault + Ledger operation and claim boundary #997.
• Adds the privileged, one-session root-owned cgroup broker boundary for required process containment.
• Authenticates the Hermes peer with SO_PEERCRED, /proc start time, and pidfd identity; cleanup revalidates identity after move-out and fails closed on any mismatch.
• Removes the direct cgroup-root fallback from required production containment; retains it only for non-required local fixtures.
• Prevents temporary Python guard bytecode caches from being counted as child disk growth when CI does not export PYTHONDONTWRITEBYTECODE.

Verification

• Exact candidate head: cfcb8fdf22a7a3d49f1bd67ca3853d0d2d23b6a5; live main: 233314a944892fbd2b269df8b24fdafc1ce21bc5
• Exact-tree custody: clean; tree deeb33793a3886e92473b3cbdf71f545c216cb86f0566fc936980a6dae7e6e43; diff SHA256 b3edd508983c9f5d4caca68ad58f36063ed1cef1f277c7498b37d19383f8ab92
• Reproduced the CI regression with PYTHONDONTWRITEBYTECODE absent: guard instrumentation bytecode caused false resource_limit results. The two focused resource regressions now pass with that variable absent.
• Focused and broker checks: 21 passed, 1 skipped; full host suite: 2935 passed, 8 skipped; generated build check/smoke, YAML parse, Python compilation, README count, and git diff --check: passed
• Fresh independent exact-tree review of the final delta: passed; no security concerns or logic errors were identified. The final Windows fix serializes RunStore.load() with atomic state replacement and adds a lock regression test.
• Exact-head CI first exposed an over-specific Python 3.11 claim assertion; eb72fb9 now derives the expected claim from the observed platform status.
• Exact-head GitHub Actions matrix is running after the cfcb8fd push; merge remains gated on every required check completing successfully.

Claim boundary

This is offline acceptance-harness hardening evidence only. It does not claim Docker execution, Iron Bank acceptance, ATO, Certificate to Field, IL5/IL6 authorization, or Government POC approval.

Closes #997