chore: add bare timeseries tag, remove ineffective modality field

chore: fix modality field, drop modality tag, sync language

chore: translate to English, sync source metadata, add format:tsfile tag

chore: translate README to English and add format:tsfile tag

chore: normalize tsfile dataset metadata

Restore dataset card and add timeseries modality tag

Upload README.md with huggingface_hub

Rewrite dataset card in English; add tsfile tag

Organize GiftEval TsFiles by original frequency

Copy GiftEval TsFiles into frequency directories

Refresh dataset card and viewer status

Replace with converted GiftEval subset ett1

Copy ett1 from Salesforce/GiftEval

initial commit