How do I limit a Manager to specific clients?

Managers by default only see clients they are linked to as manager (`Client.managerId`). An Admin links this as follows:

1. Open the client profile → Client info tab
2. Fill in the team member under Responsible manager
3. Save

The Manager will from that point see the client in their client list. Other clients are invisible to them. Want a Manager to have agency-wide access? Promote to Admin, or ask support for a specific override.