spec: one document, many recipients - attach: recordPrint and the fan-out scoping rule

[delchev]

Closes the "Planned" entry that named this gap.

forEach + attach: print attaches each row's own document, which is what a per-row document (a payslip) needs. The mirror shape had no syntax: one document sent to many recipients, where the rows ARE the recipients and the attachment belongs to the record they hang off - a request for quotation mailed to each invited supplier, an agenda mailed to each participant.

attach: recordPrint renders the fan-out's anchor record: fan-out-only (outside one, attach: print already renders that record), the anchor is what must satisfy the document requirement, language / languageFrom select ITS render language, and a conforming generator MUST render the document once per fan-out rather than once per recipient.

The section also settles the point the gap entry left open - an explicit scoping rule when both records are addressable: a bare path resolves against the ROW, the reserved prefix record. addresses the anchor (one field of it), the recipient may never be record-scoped, and record. outside a fan-out is rejected. Implicit mixing is how a message quotes the wrong party, and nothing in the rendered text would show it.

Also normative: a forEach on a schedules[].notify or a notifications[] entry MUST be rejected - the first already runs once per matched row, the second is about the event record, so an accepted declaration there changes nothing and sends a different message than the one written down.

Appendix A gains the attach: recordPrint row.

Proven out by the reference implementation: eclipse-dirigible/dirigible#6740.