feat(release): publish immutable core runtime identity manifest

[shiju-nv]

Summary

Development releases currently expose archives and container images through separate identity records. Publish an attested core-runtime manifest that binds archive checksums and OCI image/platform digests to one source commit and producing workflow, rejecting incomplete or inconsistent inputs before replacing development release assets.

Related Issue

Partially addresses #2946. This supplies validated core-runtime identity records and Release Dev publication; it does not complete the issue's cross-workflow resolver, VM-driver inventory, or package/E2E consumer reuse requirements, and must not close the issue. The issue is currently marked state:stale; maintainer confirmation of this contribution's scope remains separate from technical verification.

Changes

• Record each image's source commit, workflow run, OCI index/platform digests, and staged executable hashes in its producing job.
• Validate the complete standalone CLI, gateway, sandbox, and supervisor archive inventory, including checksums, archive contents, target architecture, and agreement with staged image executables.
• Reject malformed, missing, duplicated, or mismatched records before publishing a manifest. Permit reuse of completed image jobs when retrying downstream assembly within the same source and workflow run.
• Assemble and attest openshell-release-manifest.json before development asset replacement, then publish it alongside the archives. Release Tag remains a separate publication path.
• Document the manifest's scope and verification workflow, preserve the landed prerelease-installation guidance, and update release-diagnostic skills to distinguish manifest verification from existing canary coverage.

Testing

• mise run pre-commit passes — all non-Rust checks, Rust formatting, lockfile and dependency-policy checks passed; unchanged Rust Clippy is explicitly deferred to hosted CI.
• Unit tests added/updated
• E2E tests added/updated (if applicable)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (if applicable)