status: add DelegatedPrefixes for DHCPv6 prefix-delegation persistence

[dkelson]

What

Add an optional Status.DelegatedPrefixes []string field to the IPAMClaim CRD,
holding the IPv6 prefix(es) (CIDR) delegated to a pod interface via DHCPv6 Prefix
Delegation.

// The list of IPv6 prefixes (CIDR) delegated to the pod interface via DHCPv6
// Prefix Delegation, persisted so the same prefix is reproduced across pod
// churn (e.g. KubeVirt live migration)
DelegatedPrefixes []string `json:"delegatedPrefixes,omitempty"`

Why

IPAMClaim.Status already persists the interface's IA_NA addresses in IPs so an
IPAM consumer can reproduce them on a new pod for the same workload (the KubeVirt
live-migration case). DHCPv6 Prefix Delegation gives a workload an additional,
separately-allocated routed IPv6 prefix. That prefix has the same 1:1 lifecycle
as the interface address and the same migration-stability requirement: the consumer
must hand the migration-target pod the same prefix, or a guest holding the prefix on
an infinite DHCPv6 lease is stranded. No field persists it today.

The first consumer is OVN-Kubernetes' DHCPv6-PD feature (OKEP "Migration-stable DHCPv6
Prefix Delegation"), which allocates the prefix, persists it here, and re-asserts the
route and DHCP option on the migration target from this field.

Compatibility

• Additive and optional (omitempty). Existing producers/consumers are unaffected; a
  cluster running the old CRD never sets the field. No API break, no conversion.

Generated artifacts

Regenerated alongside the type change and included in this commit:

• artifacts/k8s.cni.cncf.io_ipamclaims.yaml (CRD)
• pkg/crd/ipamclaims/v1alpha1/zz_generated.deepcopy.go

(Re-run make generate before pushing if your toolchain version differs, to confirm a
clean diff.)

---

Reviewer note (mirrors the existing IPs field)

The field intentionally parallels Status.IPs in shape (a []string of CIDRs) and in
its comment, so the persistence semantics are obvious by analogy.

Summary by CodeRabbit

• New Features

  • Added a new status field to retain delegated IPv6 prefix information for IPAM claims.
  • This helps preserve prefix details across pod restarts or migration events.

• Bug Fixes

  • Improved persistence of prefix data so it is correctly stored and restored when objects are duplicated or updated.

[coderabbitai]

Walkthrough

Adds delegatedPrefixes to IPAMClaimStatus, deep-copies the slice, and exposes the field in the ipamclaims.k8s.cni.cncf.io CRD schema.

Changes

IPAMClaim delegated prefixes

Layer / File(s)	Summary
Status contract and support pkg/crd/ipamclaims/v1alpha1/types.go, pkg/crd/ipamclaims/v1alpha1/zz_generated.deepcopy.go, artifacts/k8s.cni.cncf.io_ipamclaims.yaml	IPAMClaimStatus adds delegatedPrefixes, the deepcopy path copies the slice, and the CRD schema publishes the new status array.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main change: adding DelegatedPrefixes to status for DHCPv6 prefix-delegation persistence.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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