fix: dedup state.json, prevent duplicate node entries

sources/python/main.py

@@ -124,9 +124,11 @@ server {{
         print(f"❌ {name} failed to start:\n{logs}")
         return False
 
-    # Save state
+    # Save state (dedup)
     s = load_state()
-    s.setdefault("nodes", []).append({
+    s.setdefault("nodes", [])
+    s["nodes"] = [n for n in s["nodes"] if n["name"] != name]  # remove old
+    s["nodes"].append({
         "name": name, "type": "docker", "port": int(port),
         "upstream_ip": upstream_ip, "upstream_port": int(upstream_port),
         "status": "running", "created_at": time.strftime("%Y-%m-%dT%H:%M:%SZ")