Improve failover controls and preserve manual switching state

.tmp-tests/harbor-startup-recovery-ZiMrHv/bin/sing-box

@@ -0,0 +1,11 @@
+#!/usr/bin/env node
+const fs = require('node:fs');
+if (process.argv[2] === 'check') process.exit(0);
+if (process.argv[2] === 'version') {
+  console.log('sing-box version 1.13.18');
+  process.exit(0);
+}
+if (process.argv[2] === 'run') {
+  fs.appendFileSync(process.env.HARBOR_TEST_RUN_MARKER, 'run\n');
+  setInterval(() => {}, 60_000);
+}

.tmp-tests/harbor-startup-recovery-ZiMrHv/sing-box-config.json

@@ -0,0 +1 @@
+{"outbounds":[{"type":"vless","tag":"stale-server","server":"stale.example","server_port":443},{"type":"direct","tag":"direct"}],"route":{"final":"stale-server"}}

.tmp-tests/harbor-startup-recovery-ZiMrHv/state.json

@@ -0,0 +1 @@
+{"schemaVersion":4,"revision":2,"connectionDesired":"running"}

.tmp-tests/harbor-startup-recovery-ZiMrHv/subscription-cache.json

@@ -0,0 +1 @@
+{broken