fix(plugins): retry claude plugin install|update without -y on an old CLI

An older Claude Code has no -y on `plugin install|update` and exits with
"error: unknown option '-y'", so the dashboard's Update now chain failed at
its plugin_update step (and so did Update all, the plugin buttons and the
superpowers auto-install). Those versions also predate the confirmation
prompt -y answers, so every wrapper now retries the same argv without it
when, and only when, the CLI rejects the flag. /agenthub-update, which the
failure message points users to, falls back the same way.

server/lib/cc-plugin-cli.js

@@ -130,7 +130,23 @@ function serialize(fn) {
  * @param {{timeoutMs?:number}} [opts]
  * @returns {Promise<{ok:boolean, code:number|null, stdout:string, stderr:string, args:string[]}>}
  */
-function runClaude(args, opts = {}) {
+// A Claude Code older than `plugin install|update -y` rejects the flag outright.
+// It also predates the confirmation prompt the flag answers, so the same
+// command without it is the correct retry, not a weaker one.
+const NO_YES_FLAG = /unknown option '-y'/;
+
+async function runClaude(args, opts = {}) {
+  const result = await runClaudeOnce(args, opts);
+  if (!result.ok && args.includes("-y") && NO_YES_FLAG.test(result.stderr)) {
+    return runClaudeOnce(
+      args.filter((a) => a !== "-y"),
+      opts
+    );
+  }
+  return result;
+}
+
+function runClaudeOnce(args, opts = {}) {
   const timeout = opts.timeoutMs || DEFAULT_TIMEOUT_MS;
   return new Promise((resolve, reject) => {
     // Only pin CLAUDE_CONFIG_DIR when the operator explicitly set CLAUDE_HOME