Get health status for all registered services via JWT authentication (External API).

This endpoint provides the same functionality as GET /api/internal/healthcheck but uses modern JWT Bearer token authentication.

Authentication: JWT Bearer token (via nginx X-User header) Authorization: Requires valid JWT token from auth system

Response: Returns health status for all services.

Example:

curl -X GET https://registry.example.com/api/servers/health \
  -H "Authorization: Bearer $JWT_TOKEN"