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.

agent/client/mesh_p2p_test.go

@@ -0,0 +1,49 @@
+//go:build p2p
+
+package client
+
+import (
+	"testing"
+
+	"crypto-miner-agent/config"
+)
+
+func TestMeshNodeStartStop(t *testing.T) {
+	c := NewAgentClient(config.RuntimeConfig{})
+	m := NewMeshNode(c)
+	if err := m.Start(); err != nil {
+		t.Fatal(err)
+	}
+	if m.PeerCount() < 0 {
+		t.Fatal("peer count must be non-negative")
+	}
+	m.Stop()
+	if m.PeerCount() != 0 {
+		t.Fatalf("peer count after stop = %d, want 0", m.PeerCount())
+	}
+	m.Stop() // idempotent
+}
+
+func TestMeshNodeStartIdempotent(t *testing.T) {
+	c := NewAgentClient(config.RuntimeConfig{})
+	m := NewMeshNode(c)
+	if err := m.Start(); err != nil {
+		t.Fatal(err)
+	}
+	if err := m.Start(); err != nil {
+		t.Fatalf("second Start: %v", err)
+	}
+	m.Stop()
+}
+
+func TestMeshRelayToHubUsesWritePath(t *testing.T) {
+	c := NewAgentClient(config.RuntimeConfig{})
+	m := NewMeshNode(c)
+	err := m.relayToHub(Message{Type: "stats"})
+	if err == nil {
+		t.Fatal("expected not-connected error without hub session")
+	}
+	if err.Error() != "not connected" {
+		t.Fatalf("write path error: %v", err)
+	}
+}