chore(release): verify archive layout for nullclaw CLI compatibility

[jd316]

Summary

• add scripts/verify-release-package.sh to assert release artifact names and required file layout
• run release packaging plus layout verification in CI to catch regressions before tags are cut
• run the same layout verification in release workflow before publishing GitHub release assets
• document the local archive verification step in docs/operations.md

Why

The main nullclaw CLI now installs and runs this UI from GitHub releases. This PR enforces archive shape compatibility so nullclaw ui install/run/update stays reliable.

Validation

• npm run test
• npm run check
• npm run build
• bash ./scripts/package-release.sh v0.0.0-ci release
• bash ./scripts/verify-release-package.sh v0.0.0-ci release

[jd316]

Hi @DonPrus
PR is ready and CI is green. Please merge this PR, then create and push a release tag (for example v2026.3.5) on nullclaw-chat-ui so GitHub release assets are published. Main CLI PR nullclaw/nullclaw#293 depends on this release for nullclaw ui install/run/update. 🙏