Move overview tables into STATS/ (first folder in the Files tab)

Viewer: name the split 'eval'

Viewer: databases + tasks as separate configs; typed tasks.parquet

Viewer: rename overview->databases.parquet, add tasks.parquet split

Fix card frontmatter (real YAML) + viewer config; no overview prose link

Restore card frontmatter + viewer config

Drop overview.csv prose link (file + viewer config kept)

Add overview.csv + dataset-viewer config

Add dataset-source citation to README

Add root dataset card