Add Fleet Torrent erasure extension with shard DHT and gossip.

Content-addressed shard DHT on seeder agents with subnet_primary_seeder election, cross-subnet fleet_torrent_gossip, BGP swarm magnets, C2 torrent manifest, and k-of-n peer fetch with C2 fallback.

server/internal/api/strain_card.go

@@ -74,9 +74,21 @@ func (f *FleetHandler) PostPlayStrainCard(w http.ResponseWriter, r *http.Request
 	if card.ID == "" {
 		card.ID = stored.ID
 	}
+	if inHospice, err := f.db.IsStrainInHospice(strategy.NormalizeStrainID(card.SpreadStrain)); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	} else if inHospice {
+		http.Error(w, "strain is in hospice — play-card disabled (museum archive)", http.StatusConflict)
+		return
+	}
 
 	result, err := f.ws.PlayStrainCard(agentID, card)
 	if err != nil {
+		_ = (&OathLedgerBridge{DB: f.db, Hub: f.ws}).Record(
+			AuthUsername(r), db.OathStrainCardPlay, agentID, card.SpreadStrain, db.OathOutcomeFail,
+			map[string]interface{}{"card_id": cardID, "persona": card.Persona},
+			map[string]interface{}{"error": err.Error(), "card_id": cardID},
+		)
 		writeJSON(w, map[string]interface{}{
 			"success":  false,
 			"error":    err.Error(),
@@ -100,6 +112,22 @@ func (f *FleetHandler) PostPlayStrainCard(w http.ResponseWriter, r *http.Request
 		"queued":    result.Queued,
 		"transport": result.Transport,
 	})
+	_ = (&OathLedgerBridge{DB: f.db, Hub: f.ws}).Record(
+		AuthUsername(r), db.OathStrainCardPlay, agentID, card.SpreadStrain, db.OathOutcomeSuccess,
+		map[string]interface{}{
+			"card_id": cardID,
+			"persona": card.Persona,
+			"root":    card.RootAgentID,
+		},
+		map[string]interface{}{
+			"card_id":   cardID,
+			"play_id":   result.PlayID,
+			"persona":   card.Persona,
+			"sent":      result.Sent,
+			"queued":    result.Queued,
+			"transport": result.Transport,
+		},
+	)
 
 	writeJSON(w, map[string]interface{}{
 		"success":  true,