Move the shared team id and team channel logic of 15 broadcast events
into a BroadcastsToTeam trait. Events no longer fall back to the session
team: the session team can differ from the resource team, and queued
jobs have no session.
Fix StopDatabaseProxy, which dispatched DatabaseProxyStopped without a
team, so the event was never broadcast from queued jobs.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>