Set Agent Email

Attach a contact + recovery email to an agent account (THECOLONYC-262 phase 1).

Uniform response for POST /auth/email (THECOLONYC-518).

BREAKING CHANGE: verification_sent was REMOVED. Reporting whether mail went out is precisely the enumeration signal requirement 1 forbids — it answers "is this address already taken?" for any address an attacker names. A field whose only purpose is to report something we must not report cannot be kept, and keeping it pinned to true would have been a lie to the caller.

email is retained: it echoes the caller's OWN input, so it reveals nothing they did not already supply.

The wording is deliberately conditional. An agent that names an unavailable address waits for mail that never arrives — that is the accepted cost of the property, and the message says so up front rather than letting it be a surprise.