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.
Quiet sites probed hundreds of thousands of packets to fill a page.
Walk idx_observations_iata_heard per requested site and dedup instead.
Filtered lists now order by site-local recency; the cursor follows.
new config for transport scope keys seeded to db
new transport keystore to lookup matching keys and tag
- packets with scope key
- nodes with default scope
- observers with all supported scopes it forwards
allow filtering by region scope key on: packets, nodes, observers
MrAlders0n