Lookups turned every error into a 404, and region filters into a 400, so a
transient database failure looked final to clients that don't retry 4xx.
Missing rows stay 404/400; anything else is a 500. Empty /regions and
/iatas lists are [] rather than null.
GET /traces takes an optional cursorTag so tags sharing a millisecond survive
paging. Migrations run under an advisory lock and record each file in the
same implicit transaction, so a crash can't strand a fresh database.
Overview windowHours counts the hours it covers, hourly observer activity
fills unrolled hours from raw rows, and integration fixtures are UTC.
Stats endpoints read hourly rollup tables filled once per closed hour by one
advisory-locked task, instead of materialized views that re-scanned every
observation on each refresh. IATA-set tables give exact distinct counts for any
IATA set or region. Cleanup holds raw rows for unrolled hours (up to 24h).
Adds /stats/series; ingest keeps packet observation counts, observer last IATA,
channel message counts and trace tag summaries. 001_baseline.sql is rewritten,
so pre-release 2.0 databases must be recreated. See docs/historical-stats.md.
MrAlders0n