fix(network): wired ping probe, AP/WS and systemd notify hardening

- Add hasWiredInternetProbe and export; AP mode uses it with hasInternet
- systemd-env: strip NOTIFY_SOCKET from env early; client uses unix_dgram
- Strip NOTIFY_SOCKET from frpc/ttyd spawn env in watchdog and frpc
- WS: pong miss debounce; AP net monitor consecutive-fail debounce

Made-with: Cursor

bin/clawd.js

@@ -1,6 +1,9 @@
 #!/usr/bin/env node
 'use strict';
 
+// 先于其它模块：摘掉 NOTIFY_SOCKET，避免任意子进程误发 systemd notify
+require('../lib/systemd-env');
+
 const { ClawClient } = require('../lib/client');
 const log = require('../lib/logger');