Set what members outside an agent may do with it and its sessions (owner or admin)

Inside an agent are owners, admins, the agent's admins (its admin rows, its admin teams' members and its managing team's leads) and its managing team's other members; every other member is outside it. agent_outsider_access (default use): use lets those outside read the agent's information and start its sessions, view only read its information (a start is 403 FORBIDDEN, details.reason_code role), none hides the agent from them (absent from GET /v1/agents, 404 on reads of it, and a start is 403). It applies to every agent. agent_outsider_session_visibility (default managing_team): managing_team keeps the workspace-scoped sessions of an agent from those outside it, in every list, count, read, stream and usage list; workspace lets every member see them. A session the member holds, and a people or team share naming them, still reach them; an agent still held by the 'Unassigned agents' team that migration 0243 made for agents that had no managing team is not limited, until it is moved to a real team. Both apply from the next request to sessions already made, and an open event stream ends at its next page. A key left out keeps its value; name at least one. Writes a set_agent_access_settings receipt with what changed unless nothing did (receipt_id null). The current values are workspace.settings in GET /v1/auth/me.

Auth: cookie session only; no scope. Idempotency-Key: ignored.