Expand dataset card for review: source, size, splits, construction, license, metrics, citations

Fix task_ids to Hub-recognized retrieval/similarity ids

Update README YAML frontmatter: cc-by-nc-4.0, languages, tasks, retrieval tags

Fix viewer metadata: push ukr-eng

Fix viewer metadata: push swe-eng

Fix viewer metadata: push spa-eng

Fix viewer metadata: push rus-eng

Fix viewer metadata: push ron-eng

Fix viewer metadata: push por-eng

Fix viewer metadata: push nld-eng

Fix viewer metadata: push ita-eng

Fix viewer metadata: push deu-eng

Fix README YAML for dataset viewer (dataset_info list + default)

Rename parquet shards to train-00000-of-00001.parquet style

Fix test split: line-level pairs aligned with BitextMining format

initial commit