- Add `user_edited` field to QuoteItem type to gate AI rewrites on user-edited content
- Add idempotent migration script to add and backfill the `user_edited` field across quote items
- Replace plain Select components with searchable SupplierSearch combobox across order and quote pages
- Add working days calculation utility and aged quote warning badges for overdue quotes
- Implement expandable row previews in the quotes list view
- Add full AI rewrite workflow: backend API endpoint, frontend modal, and n8n workflow definition
- Update package scripts for the new migration
