Mute Non-Essential Emails (confirm)

The ONLY mutating half of the mute flow: submitted by the button on the GET confirmation page (same signed token, carried in the query string). Verifies the token, then mutes non-essential forwarding for that user's relay alias (sets status=disabled). Essential mail (interview invites, assessment requests, offers, application confirmations) is still forwarded; every inbound message is still captured + classified into the AI Applyd inbox. Redirects (302) to the web inbox with forwarding=stopped (or forwarding=invalid on a bad token).