Splits monolithic cluster.rs into tidal-server/src/cluster/ modules. Adds redeliver-missed
relay, bounded HLC drift, lag tracking, and reconcile idempotence. Five new tier-3 test suites
(chaos, lifecycle, multiproc, region, routes, runbook) all green. Docs, CHANGELOG, and ROADMAP
updated with G4/G5/G6 known gaps.
Resolves the 142 findings from tidal/docs/reviews/CODE_REVIEW_m0-m10.md across
the engine, server, net, and CLI surfaces:
- WAL/session-journal durability, checkpoint format, and crash-recovery hardening
- Replication shipper/receiver, tenant isolation, and migration paths
- Cluster scatter-gather, router, standalone server + health/offload endpoints
- tidalctl refactored into command modules with JSON output and WAL-state tooling
- Cohort, governance, signal-ledger, and vector-registry correctness fixes
- Expanded UAT/integration/durability test coverage across all milestones