Daily CSV Sales & Purchases Sync

I need a Google Sheet set up so I can drop in one CSV file each day and have both my sales and purchase figures flow into the right places without extra cleanup. Every import must:
• recognise whether the rows belong to “Sales” or “Purchases” and append them to the correct tab,
• keep existing historical data intact, and
• preserve date, currency, and quantity formats exactly as they appear in the source files.

If a lightweight script (Apps Script) or an IMPORTRANGE/IMPORTDATA-based approach makes the daily upload easier, please include it; otherwise a clear step-by-step workflow inside the Sheet is fine. The finished file should be share-ready in Google Drive, with a brief note or Loom showing how the daily CSV import is performed and how to roll back in case of a mis-upload.