lokahi: interop actor, cross-safe happy path (phase 3)

The timestamp-lockstep verifier (port of op-supernode's interop activity): observe → pure decide → WAL → apply rounds, cold start + 7-day log backfill, verifiedDB+WAL, per-chain logsDBs, invalidated-output archive. Cross-safe promotion over the chain lifecycle (trivial pre-activation, held during backfill, verification-driven after), finality bound, halted state, conservative-minima sync status. Message-validity rules shared via kona-interop (the proof side must apply identical rules).

Work items are the sub-issues.

🤖 *Co-created with Claude (Fable 5)*

Start by reviewing the sub-issues, since this issue identifies the work items but no files, tests, or entry points. Trace the timestamp-lockstep verifier requirements and the shared message-validity rules in kona-interop; done requires the listed lifecycle, backfill, WAL, archive, finality, halted-state, and sync-status behaviors to be implemented consistently.

Written by the indexing model from the issue text.