Add server subnet discovery store, API, and agent policy push.

server/internal/db/oath_ledger.go

@@ -15,6 +15,7 @@ const (
 	OathStrainCardPlay       = "strain_card_play"
 	OathCourtL4Decision      = "court_l4_decision"
 	OathSpreadAttempt        = "spread_attempt"
+	OathSpreadDiscoveredHost = "spread_discovered_host"
 	OathStrainHospice        = "strain_hospice"
 	OathReconScan            = "recon_scan"
 )