List organization agents

Retrieve all agents for the authenticated organization.

Returns a paginated list of agents with basic information including:
- Agent ID and name
- Agent type (inbound/outbound)
- Active status
- AI provider information
- First message configuration
- Created/updated timestamps

Filtering and pagination:
- Optional filter by agent type (inbound or outbound)
- Sorted by newest agent first (created_at DESC)
- Default limit: 50 agents per page (max 100)
- Use offset for pagination

Authentication:
- API key with READ or READ_WRITE permission, or
- OAuth access token granted the `agents:read` scope