chore: remove Syncthing node — service retired

atlas.json

@@ -25,15 +25,6 @@
       "status": "active",
       "parent": "ubuntu-pc"
     },
-    {
-      "id": "syncthing-ubuntu",
-      "label": "Syncthing",
-      "type": "service",
-      "description": "Ubuntu PC ↔ Windows PC のリアルタイムファイル同期。posimai-project フォルダを双方向同期。",
-      "url": "http://100.77.11.43:8384",
-      "status": "active",
-      "parent": "ubuntu-pc"
-    },
     {
       "id": "windows-pc",
       "label": "Windows PC",
@@ -185,10 +176,8 @@
 
     { "from": "windows-pc",       "to": "ubuntu-pc",       "type": "connects", "label": "SSH / posimai-dev" },
     { "from": "android-phone",    "to": "posimai-dev",     "type": "connects", "label": "Tailscale HTTPS" },
-    { "from": "windows-pc",       "to": "syncthing-ubuntu","type": "connects", "label": "ファイル同期" },
 
     { "from": "posimai-dev",      "to": "ubuntu-pc",       "type": "runs-on" },
-    { "from": "syncthing-ubuntu", "to": "ubuntu-pc",       "type": "runs-on" },
     { "from": "gitea",            "to": "synology",        "type": "runs-on" },
     { "from": "uptime-kuma",      "to": "synology",        "type": "runs-on" },