feat(pipeline): surface per-distribution RDF-validity verdicts

[ddeboer]

Closes #469. Part of the distribution-health feature: netwerk-digitaal-erfgoed/dataset-register#2103.

What

Wires @lde/distribution-health into @lde/pipeline so every distribution the pipeline touches gets an RDF-validity verdict, surfaced as a plain TypeScript value through a new reporter callback. The pipeline emits no RDF and coins no vocabulary — consumers map the verdict to their own RDF (the “RDF emission & vocabulary boundary” decision in #2103).

New surface:

ProgressReporter.distributionValidated?(distribution: Distribution, verdict: ValidityVerdict): void

Behaviour

• Deep verdict from the import outcome:
  • import failure → parse-error, surfaced even when the dataset is then skipped (the previously-silent drop that motivated #2103);
  • import success → valid, or empty when it yielded no triples.
  • Guarded on an actual data-dump import, so native SPARQL endpoints (not imported) carry no deep verdict.
• Shallow verdict from the probe's existing body validation, per probed distribution that yields a validity signal.
• Each verdict carries the distribution's observed source fingerprint; the fingerprint is also added to the reachability result (DistributionAnalysisResult.fingerprint) so it is the shared key across the reachability and validity rails.

Tests

311 pipeline tests pass (5 new, behaviour-asserted through the reporter): deep invalid / valid / empty, shallow invalid, and the reachability fingerprint. Lint + typecheck clean.

Notes

• The success path reconstructs an ImportSuccessful to feed the shared mapper. A possible later cleanup is to compute the verdict where the real import outcomes live (importResolver) and thread the fingerprint in; left as-is for now since it's localised.
• Vocabulary/RDF stays out of LDE entirely (returns TS); the def.nde.nl mapping lands in the consumers (epic tasks 4 & 5).