feat: private networking

[mweibel]

Changes

• CloudscaleCluster now supports:
  • Managed or BYO networks
  • Load balancer (public or private VIP)
  • Floating IPs
  • Servers/Nodes with public and/or private networks attached
• API updates – Extended v1beta2 CRDs (cloudscalecluster_types.go, cloudscalemachine_types.go, condition_types.go) and regenerated deepcopy/CRDs.
• Controller logic – Added new reconcilers:
  • cloudscalecluster_floatingip.go (+tests)
  • cloudscalecluster_loadbalancer.go (+tests)
  • cloudscalecluster_network.go (+tests)
• Validation/webhooks – Updated webhook implementations and tests for the new fields.
• Testing – Added unit tests for new services and controllers; expanded e2e suite with BYO networking flavors (fip, public‑lb‑private‑nodes, byo‑network).
• Cluster templates – New kustomize templates for each network flavor under templates/.
• CI / Makefile – Updated GitHub workflows and Makefile targets to run the new e2e tests and generate updated manifests.
• Documentation – Updated README.md feature table, environment variable table, and added networking proposal docs.

How to test

Best is to use a local tilt installation as indicated in the README and in previous PRs. Then, apply the new flavors using the tilt-builtin apply or by using envsubst on the newly created flavors in templates/.
N.B.: For BYO networks with private nodes, you'll need a private network with a NAT gateway set up by contacting support.