Admin: allow deleting teams and removing members from teams

- Motivation:
Admins need to manage organization teams fully, including deleting teams and removing members.

- Proposed solution:
Backend: ensure endpoints for deleting a team and removing a member from a team exist in `backend/aci/control_plane/routes/organization/organizations.py` and are wired to CRUD in `backend/aci/common/db/crud/teams.py` with proper access control. Frontend: add actions in `frontend/src/features/settings/components/teams-settings.tsx` and `members-settings.tsx` to trigger these operations with confirmations.

- Additional context:
- Respect org role checks and guardrails.
- Update UI states and refresh lists after actions.