Connected-agent governance: admin org-wide roster & revoke

Owners and admins can now see every agent connected to their org's shared spaces under Settings → Audit & governance → Connected agents. The roster shows each member, their connected client, connection date, and last-used date; filter by member, client, activity (active vs stale), or connected date range. Revoking a connection from the roster cuts the agent's access immediately — the same hard-kill used by the self-service revoke on the personal Agent settings page.