Sub-ticket of PLUTO-218 Soporte parity P2: server actions postSupportReply(staff) + closeAndNotify — reuse P0/PLUTO-203 shared email leg (sendAdminEmail, verified soporte-evolutiva-pluto@ From, idempotency, rate-limit); KEEP manageSupport-EXCLUSIVE gate (no fullAccess/manageUsers/adminConsole escape). Audit design-ping on email+gate before impl. · pluto