Public dataset catalog with local indexed row counts and recorded timestamps

Distinct from /api/v1/coverage, which is an operations snapshot. By default this route serves HTML. Request application/ld+json or application/json for a JSON-LD DataCatalog, or text/markdown for a Markdown table. Counts come from the materialized local coverage table; a missing coverage row appears as zero with a null timestamp. Recorded timestamps may be local ingestion times or source-event dates depending on the dataset, and do not prove current upstream completeness. The DataCatalog dateModified is the response generation time, not a source update time.