Import Contacts

Imports the selected rows of the import template CSV (multipart/form-data: the file as 'file' and 'selections', a JSON array of { rowId } from the analysis). The file is analysed again and each selected row becomes a supplier + CIS subcontractor with an import note and, when the row carries a verification number, date and tax status, a manual verification (firing subcontractor.created, as any create); one bad row never aborts the rest, and a selected row with a skip reason fails with that reason. A file with no rows, not CSV, or no selection is 400.