fix: 2026-06-04 audit pass — README, USB pack, multi-area fixes

WS ticket dashboard auth, builder universal signing/size limits/fusion obfuscation/dropper bundles, Path Tracer WireGuard topology, SessionGate degraded mode and download timeouts, server bootstrap (data dir, cloudflared dedupe, config port precedence), agent mesh/miner/spread fixes. README refreshed; usb bundle repacked; PROBLEMS.md audit log updated.

server/main_test.go

@@ -7,6 +7,18 @@ import (
 	"testing"
 )
 
+func TestValidateListenPort(t *testing.T) {
+	if err := validateListenPort(8989); err != nil {
+		t.Fatalf("8989 should be valid: %v", err)
+	}
+	if err := validateListenPort(0); err == nil {
+		t.Fatal("port 0 should be invalid")
+	}
+	if err := validateListenPort(70000); err == nil {
+		t.Fatal("port 70000 should be invalid")
+	}
+}
+
 func TestResolveDataDirAbsolute(t *testing.T) {
 	abs := filepath.Join(t.TempDir(), "data")
 	got := resolveDataDir(abs, "C:\\project")