feat(api): allow scoped skill content publication without management rights

[ctkm-aelf]

Summary

A dedicated worker can upload skill packages and publish new versions using ornn:skill:publish, without the broad ornn:skill:update permission. Updates still require ownership or an explicit per-skill write grant. Publish-only callers cannot change existing visibility, permissions, ownership, bindings, or tags, or delete skills or versions.

An explicit POST /skills?public=true creates a readable skill at insert time; ordinary creation remains private. Existing create/update permissions retain their behavior. The dedicated role contains only ornn:skill:read and ornn:skill:publish.

Linked issue

Closes #1247

Type of change

• New feature (feat:)
• Docs (docs:)

Commit decomposition

• Each commit is self-contained and covers one logical change.
• Code and regression tests are separate from documentation and release notes.
• No unrelated refactors or Co-Authored-By trailers.

Changeset

• Added .changeset/content-only-publication.md with an ornn-api minor bump.

Testing

• Full workspace TypeScript check passed using the installed TypeScript 6 executable.
• Lint passed with zero errors and two existing warnings; assistant KB regeneration and diff checks passed.
• Added regressions through the real proxy-auth and CRUD routes for machine identity, exact object grants, malformed public queries, JSON/multipart visibility attempts, and management/deletion denials. Added service and Mongo integration coverage for initial visibility.
• Hosted CI passed: 2,603 API tests, 672 web tests, 38 TypeScript SDK tests, Python SDK checks, API coverage 95.54% (75% gate), and both Docker builds. The new machine-identity/object-grant/denial cases and Mongo initial-visibility integration test executed successfully. All code-scanning checks passed.

Notes for the reviewer

The companion NyxID PR #1588 supplies a separate curation service-account identity, exact catalog-service assignment grants, and an explicit method/path policy on a dedicated Ornn catalog target. That existing proxy policy is required to exclude unrelated authenticated Ornn routes such as assistant chat; Ornn permission names alone do not restrict those routes. Existing skill owners grant the machine UUID write access once. Content updates then require no per-change review.

The change is additive and does not provision roles, credentials, or live catalog services. This feature PR targets develop according to the repository workflow.