- Replace TOCTOU race (separate Load+Save) with atomic
SaveJobTypeConfigIfNotExists on ConfigStore and Plugin
- Replace ineffective polling loop with single GetMaster call using
30s context timeout, since GetMaster respects context cancellation
- Add unit tests for SaveJobTypeConfigIfNotExists (in-memory + on-disk)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>