Render agent activity from canonical events

Status: accepted

Mevedel renders compact agent activity rows from canonical tool and lifecycle events: Started PATH, SendMessage: PATH, InterruptAgent: PATH, and Waiting for agents. SendMessage render-data names its disposition: message queued, started, or waiting for a slot. Settled WaitAgent calls render WaitAgent: agents (OUTCOME); consecutive visible waits retain the final row with a count. Canonical events remain unchanged, and UI code does not maintain an independent activity state that can diverge from agent turns, mailbox delivery, or tool settlement.