✨ feat(api): add Architecture and NodeInfo types to core API

[bryan-cox]

Summary

• Add centralized Architecture type and NodeInfo struct to both v1beta1 and v1beta2 core APIs
• These types enable infrastructure providers to implement the status.nodeInfo field on Infrastructure Machine Templates as defined in the Opt-in Autoscaling from Zero proposal
• Eliminates the need for providers to independently copy and maintain these type definitions, ensuring consistency across the Cluster API ecosystem

Background

The Opt-in Autoscaling from Zero proposal introduced the concept of scaling from zero replicas, which requires infrastructure providers to expose node capacity and metadata information via a status.nodeInfo field on Infrastructure Machine Templates.

Currently, all CAPI providers following this proposal must either:

1. Copy the same type definitions into their codebases, or
2. Reuse/import from other providers

This leads to code duplication and potential inconsistencies. This PR centralizes these types so all providers can import and use the same standardized definitions.

You can see the duplication happening in both CAPA and CAPZ so far:

1. https://github.com/kubernetes-sigs/cluster-api-provider-aws/blob/ea252592b45d62f2eeab6b6ace2c35b2f7bad2c2/api/v1beta2/awsmachinetemplate_types.go#L28
2. feat: Implement autoscaling from zero by auto-populating AzureMachineTemplate capacity/nodeInfo cluster-api-provider-azure#6013

Changes

• Added Architecture type with constants: amd64, arm64, s390x, ppc64le
• Added NodeInfo struct with architecture and operatingSystem fields
• Types added to both api/core/v1beta1 and api/core/v1beta2
• Ran make generate to update generated files

Provider Usage

// v1beta2
import clusterv1 "sigs.k8s.io/cluster-api/api/core/v1beta2"
arch := clusterv1.ArchitectureAmd64

// v1beta1
import clusterv1beta1 "sigs.k8s.io/cluster-api/api/core/v1beta1"
arch := clusterv1beta1.ArchitectureAmd64

Test plan

• make generate passes
• make test passes
• make lint passes (Go linting; Dockerfile lint requires Docker daemon)

🤖 Generated with Claude Code

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[bryan-cox]

Should this PR get merged, I'm happy to go update both CAPA and CAPZ to use this centralized implementation.