Bulk edit core material pricing via CSV upload

Update core material pricing in bulk by downloading the CSV, editing only the pricing, margin and taxes fields, and uploading it back.

1. Use bulk actions to edit core material pricing, such as MR grade materials.

   ✓ Checked in the product on 15 October 2026

2. Download the CSV for sales channel properties and pricing.

   ✓ Checked in the product on 15 October 2026

3. Edit only the pricing, margin, and taxes fields.

   ✓ Checked in the product on 15 October 2026