fix: restore curated metadata dropped by generator (papers/arXiv, creators, source_datasets)

fix: correct dataset-viewer config paths to actual data dirs (nested_rt_path)

docs: regenerate dataset viewer configs from schema

docs: add source data configs for .jsonl.gz files (21 entities)

docs: add YAML configs for dataset viewer (127 subsets)

Super-squash branch 'main' using huggingface_hub