Composer validator now takes senderType (system|user) and an
attachments[] array, and the service dispatches across two paths:
the system path uses lib/email/index.ts with port-config noreply
identity and logs signed_doc_emailed when an attachment matches a
document's signed PDF; the user path stays on the existing personal-
account flow but is gated by the new email.allowPersonalAccountSends
toggle and the attachment fileIds are persisted on email_messages.
sendEmail in lib/email accepts attachments and resolves them from
MinIO with cross-port enforcement.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>