Match pasted text or a CSV before adding

Paste company numbers or names (one per line), or send a CSV file's text with source: "csv". The company number column is found by its header ("Company number", "CRN", "Reg no"…) or its contents; names are matched against the register (exact name after ignoring punctuation and LIMITED/LTD; a registered postcode column settles ties). Your reference, tags, note and postcode columns are picked up too. Nothing is added: send the matched numbers to POST /lists/{id}/items. Rows come back as matched, ambiguous (with up to 5 candidates to choose from), not_found or already_on_list, and rejected rows carry the reason. CSV import needs a plan with CSV (Pro, Team or a paid API plan); pasting is on every plan.