加速数据库上传：hf_transfer加速库

fix: load .env.local with override and handle empty token

fix: ignore dummy HF_TOKEN and load env vars

feat: improve data sync scripts and handling

Feat: add dotenv support for local env loading

Fix: improve error handling in upload script for auth failures

Feat: implement dataset-based data persistence and remove baked-in db

Feat: implement dataset-based data persistence