[INF-1722] Show WAL gaps and PostgreSQL maintenance progress

[thesyncim]

Ticket

INF-1722

Summary

• Compare exact source, captured and applied LSNs; split uncaptured/replay/end-to-end WAL gaps and measure actual source, capture and replay rates.
• Show VACUUM/autovacuum, VACUUM FULL and index-build phases, counters and blockers. Percentages describe the current phase only; unknown totals stay unknown.
• Isolated, authenticated read-only diagnostics: shared 5s samples, bounded SQL, permission/staleness handling, no changes to replay, acknowledgement, storage or cutover.

Validation

• Full Go race suite, vet, and JavaScript regressions.
• PostgreSQL 16/17/18 matrix, twice with race detection: SQL-verified LSN arithmetic, real index waits, VACUUM/FULL, permissions, database isolation and read-only/timeouts.
• Full migration E2E and exact Linux image E2E: final source/target row counts and hashes match.
• v68-to-new whole-controller upgrade during replay: settings preserved, counters advance, final data checks pass.
• Actual browser: advancing vacuum bar, index blockers, unmeasured phases, live LSNs/rates, configuration and stale/error clearing.

Rollout

Candidate v69 passed exact-image E2E; live deployment is awaiting explicit approval from the cluster guard. c3 remains on v68, running unchanged. The rollout must preserve its PVC, slot, saved settings and receipts; no recopy, index changes, source writes or cutover. Durable formats are unchanged, so image rollback is compatible.

Screenshots

Real local PostgreSQL fixtures, not mockups.

LSNs and split WAL gaps

VACUUM progress

Index waits and VACUUM FULL