fix(actions): ssh channel pins known_hosts beside key (no HOME dependency)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/actions/channels/ssh.js

@@ -1,4 +1,5 @@
 import { spawn as nodeSpawn } from 'node:child_process';
+import { dirname, join } from 'node:path';
 
 const ID_RE = /^[a-z0-9-]+$/;
 
@@ -11,8 +12,11 @@ export function restartService({ ip, actionId }, {
   spawnImpl = nodeSpawn
 } = {}) {
   if (!ID_RE.test(actionId || '')) return Promise.reject(new Error(`invalid action id: ${actionId}`));
+  // Pin known_hosts beside the key (writable, void-owned) so the channel doesn't
+  // depend on the service's HOME for ~/.ssh.
+  const knownHosts = join(dirname(keyPath), 'known_hosts');
   const args = ['-i', keyPath, '-o', 'BatchMode=yes', '-o', 'StrictHostKeyChecking=accept-new',
-    `${user}@${ip}`, actionId];
+    '-o', `UserKnownHostsFile=${knownHosts}`, `${user}@${ip}`, actionId];
   return new Promise((resolve, reject) => {
     const child = spawnImpl('ssh', args);
     let out = '', err = '';