fix(observers): preserve advert pages with missing origin keys (#138)

* test(observers): cover adverts with a missing origin key

* fix(observers): preserve advert pages with missing origin keys

db/sqlc/queries.sql.go

@@ -2860,7 +2860,7 @@ SELECT
   po.snr,
   po.hop_count,
   n.name AS node_name,
-  encode(p.origin_pubkey, 'hex') AS node_public_key
+  COALESCE(encode(p.origin_pubkey, 'hex'), '')::text AS node_public_key
 FROM packet_observations po
 JOIN packets p ON p.packet_hash = po.packet_hash
 LEFT JOIN nodes n ON n.public_key = p.origin_pubkey
@@ -2892,6 +2892,7 @@ type ListObserverAdvertsRow struct {
 
 // Returns advert packets (payload_type=4) heard by a specific observer.
 // Pass cursor=0 to start from the beginning, or the last seen id for pagination.
+// Keep missing-origin adverts; the generated key field expects a string, not NULL.
 func (q *Queries) ListObserverAdverts(ctx context.Context, arg ListObserverAdvertsParams) ([]ListObserverAdvertsRow, error) {
 	rows, err := q.db.Query(ctx, listObserverAdverts, arg.ObserverID, arg.Column2, arg.Limit)
 	if err != nil {