Extract repeated `new java.util.HashSet<>(Set.of(TrainingLabel.KURRENT_RECOGNITION))`
into a `kurrentLabels()` helper in TrainingBlockQueryTest and add `import java.util.HashSet`.
Add clarifying comments on the two person-scoped queries in TranscriptionBlockRepository
explaining that they use `MEMBER OF d.trainingLabels` — aligned with the pre-existing
`findEligibleKurrentBlocks()` pattern.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>