fix(plugin): guard against undefined step.name in retryFailedStep

In `run-workers` mode, `event.step.started` can fire with a step
object whose `name` property is undefined. The `ignoredSteps` loop
then calls `.startsWith()` and `.match()` on `undefined`, crashing
the worker with:

  TypeError: Cannot read properties of undefined (reading 'startsWith')

Add an early return when `step.name` is falsy so the plugin skips
the step instead of crashing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: gololdf1sh

lib/plugin/retryFailedStep.js

@@ -111,6 +111,7 @@ export default function (config) {
   }
 
   event.dispatcher.on(event.step.started, step => {
+    if (!step.name) return
     for (const ignored of config.ignoredSteps) {
       if (step.name === ignored) return
       if (ignored instanceof RegExp) {