fix(distribution-monitor): tolerate lock timeout on boot-time index check

[ddeboer]

Problem

The status monitor crash-loops on startup with:

Failed to start monitoring service
query: CREATE UNIQUE INDEX IF NOT EXISTS latest_observations_monitor_idx ON latest_observations (monitor)
PostgresError 55P03 (lock_not_available)

latest_observations is a materialized view, and the boot path always runs a CREATE UNIQUE INDEX IF NOT EXISTS to provide the unique index that REFRESH … CONCURRENTLY requires. Even the IF NOT EXISTS form must take a SHARE lock on the view before it can skip, and that lock conflicts with the EXCLUSIVE lock held by a REFRESH … CONCURRENTLY running in another instance.

During a rolling deploy the old and new pods overlap (default RollingUpdate, maxUnavailable: 0), so the new pod's index re-check waits on the old pod's refresh. With the per-connection lock_timeout (30s) introduced earlier, that wait now raises 55P03 — and because the statement was unguarded, it aborted startup and the monitor crash-looped indefinitely, leaving the status site without availabilities.

Fix

Wrap the index creation in ensureLatestObservationsIndex(), which swallows a 55P03 lock-timeout and lets startup proceed. Whenever the view is being refreshed the index already exists, so a failed re-check is harmless. Any other error still propagates unchanged.

This keeps RollingUpdate (two overlapping pods) working — no deployment-strategy change needed.

Changes

• store.ts — extract ensureLatestObservationsIndex() (tolerates 55P03, re-throws everything else) and isLockNotAvailable() (detects the SQLSTATE through drizzle's wrapped cause chain).
• store.test.ts — unit tests for both helpers (fast, no lock-wait): swallow vs. re-throw, and SQLSTATE detection across nested causes and non-object inputs.
• vite.config.ts — autoUpdate raised the coverage thresholds to match.

Notes

This addresses the crash-loop. A separate, pre-existing concern remains: the observations table has no retention/pruning, and a REFRESH … CONCURRENTLY was observed wedged for hours — worth its own issue.