[Feature Request] More fields for correspondents (IBAN, VAT ID, email domains, aliases, description)

Description Correspondents currently have a name and matching rules. Storing a few more facts per correspondent would help in three places: 1. Search — find all documents from the sender with IBAN X or VAT ID Y, or look up a correspondent's details without opening a document. 2. Matching on consumption — a document containing a known IBAN, VAT ID, email address/domain or phone number belongs to that correspondent, much more reliable than name matching. 3. AI suggestions — give the AI a short description and the aliases, so it picks the existing correspondent instead of inventing a new one (#14257, #13403). Fields I'd suggest: aliases, description, email addresses/domains, IBAN(s), VAT ID, phone, address, customer number. Ideally via custom fields on correspondents, as proposed in #10826 (27 upvotes, auto-closed). Related: #10826, #371, #13403 (description field for AI), #14077 (aliases and merging). Other <details> <summary>Details and suggestions</summa…