Improve portable launch, forge persistence, and operator auth UX.

Persist build extra_files for Build Manager history, print dashboard login on every start, add libp2p for Mesh P2P forge, defer WebSocket until login, and split devrun.bat from LAUNCH.bat with USB deck auto-detection.

server/internal/api/server_policy_test.go

@@ -0,0 +1,31 @@
+package api
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestServerPolicyJSONRoundTrip(t *testing.T) {
+	in := ServerPolicy{
+		MaxAgents:              128,
+		LogAgentConnections:    true,
+		LogShareSubmissions:    false,
+		LogPoolTraffic:         true,
+		StrictWalletValidation: true,
+		MaxBuildSizeMB:         64,
+		PoolReconnectSeconds:   30,
+	}
+
+	data, err := json.Marshal(in)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var out ServerPolicy
+	if err := json.Unmarshal(data, &out); err != nil {
+		t.Fatal(err)
+	}
+	if out != in {
+		t.Fatalf("round-trip mismatch:\n  got  %+v\n  want %+v", out, in)
+	}
+}