Prepare pre-1.0 native artifact evidence

[RobLe3]

Summary

• align the component's declared pre-1.0 qualification boundary where needed
• add a clean-source, native-target artifact builder with locked online/offline installation checks
• emit content-free, non-authorizing artifact fragments for later six-component composition

Safety

• does not publish, deploy, provision a runner, or assign a stable version
• leaves the candidate and qualification campaign open

Local verification

• component tests and builder-description contract passed
• native macOS artifact build was exercised where the component supports macOS; Linux-only builders were checked for fail-closed target refusal