Fix worker current test tracking: use report.node.workerid not report.workerid
In pytest-xdist, the worker ID is on report.node.workerid (WorkerController),
not report.workerid directly. Fall back to node attribute so [idle] entries
are replaced with actual test names in CTRL monitor lines.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>