feat: add discovery context annotations for project-scoped resources

[scotwells]

Summary

This PR adds discovery.miloapis.com/parent-contexts: Project annotations to all CRD manifests in the compute repository, and the corresponding +kubebuilder:metadata:annotations markers to the Go type definitions.

What these annotations do

The Milo API server includes a discovery filter that uses discovery.miloapis.com/parent-contexts annotations on CRD metadata to determine which resources to surface in API discovery responses. When a client queries API discovery within a Project context (e.g., against a project's dedicated control plane), the filter returns only those resources annotated with Project as a parent context.

Without these annotations, compute resources would be invisible in discovery when clients query within a Project context.

Affected CRDs

• instances.compute.datumapis.com
• workloaddeployments.compute.datumapis.com
• workloads.compute.datumapis.com

Changes

• Added discovery.miloapis.com/parent-contexts: Project to metadata.annotations in all three CRD YAML files under config/base/crd/bases/
• Added // +kubebuilder:metadata:annotations="discovery.miloapis.com/parent-contexts=Project" marker to the root Go types in api/v1alpha/ so the annotation survives future task generate runs

Test plan

• Verify CRD YAML annotations are present in config/base/crd/bases/
• Apply CRDs to a cluster connected to a Milo API server with the DiscoveryContextFilter feature gate enabled
• Confirm compute resources appear in API discovery when querying within a Project context
• Confirm compute resources are absent from discovery when querying outside a Project context (e.g., Platform context only)

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