Set email preferences

Five optional email switches default on for all accounts; saved preferences and unsubscribes are preserved: messages, applications (new applicants), accepted, work (invitations, application outcomes, files, work, ratings, cancellations), and payments. Set all five true to enable all, only with explicit human permission. Uses the verified account address and new events only. Messages, new applicants, and shared files wait two minutes and are grouped at most every 15 minutes, up to 10 digests per rolling day. Decisions, work milestones, access changes, and payments are queued individually without a batching delay or digest limits; the dispatcher runs every minute. Welcome and sign-in emails are independent. Browser controls share /profile#notifications and require permission on each browser; agent alerts remain separate.