Closes#33617. Adds additive _meta.hermes.sessionProvenance to ACP session
surfaces so clients can detect compression-driven internal session rotation
without parsing status text, guessing from token drops, or reading state.db.
Derived on demand from the existing compression chain (parent_session_id /
end_reason) — no new persisted state, no schema change, no ACP protocol change.
ACP session_id stays the stable client handle.
- acp_adapter/provenance.py: derive provenance from SessionDB
- server.py: attach _meta to new/load/resume responses; emit a
session_info_update when the internal head rotates during a prompt
