[Release] Prepare pilot plugin restructure release readiness checklist

[ashleyshaw]

Release Summary

Prepare the release readiness checklist for the first portable AI plugin restructure milestone.

Parent epic: #285.

Milestones / Checklist

• Release goal described.
• Versions/tags mapped.
• Parent epics and child issues linked.
• Validation results recorded.
• Plugin install tests recorded.
• Docs/changelog prepared.
• Release notes drafted.
• QA/staging verified.

Acceptance Criteria

• Release completed and verified.
• Documentation/changelog updated.
• Release notes published or prepared for maintainer approval.

Additional Context

This release should cover the pilot restructure milestone, not the full future plugin family.

Definition of Ready (DoR)

• Release goal and scope defined.
• Milestones and checklist mapped.
• Estimate added.

Definition of Done (DoD)

• All checklist and acceptance criteria completed.
• Documentation/changelog updated.
• Approved by maintainer.

[linear-code]

LS-636