Replace Netdata with Beszel as CapRover's built-in server monitoring solution.

See https://github.com/caprover/one-click-apps/pull/1286

Netdata is a powerful monitoring platform, but it has grown significantly in scope and complexity beyond what CapRover needs. CapRover primarily needs a simple way for users to view server and container resource usage, without the overhead of a full observability platform.

Beszel is more lightweight, has a simpler UI, and is more focused on the core metrics relevant to CapRover users. Moving to Beszel would provide a cleaner monitoring experience, reduce resource overhead, and make the monitoring integration easier to maintain.