Implements testConnection and listResources against the NetBird
Management API (/api/peers), mapping connected/disconnected peers to
resource health. Defaults to the NetBird Cloud API but respects an
optional baseUrl override for self-hosted management servers.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BbJV5nm8KPVH1oNJYKpnoF