Container mode now bind-mounts ${stateDir}/home to /home/hermes so the
agent's home directory survives container recreation. Previously it lived
in the writable layer and was lost on image/volume/options changes.
Also passes MESSAGING_CWD to the container so the agent finds its
workspace and documents, matching native mode behavior.
Other changes:
- Extract containerDataDir/containerHomeDir bindings (no more magic strings)
- Fix entrypoint chown to run unconditionally (volume mounts always exist)
- Add schema field to container identity hash for auto-recreation
- Add idempotency test (Scenario G) to config-roundtrip check
