chore: remove unused theme Node manifests

[yada]

Summary

• remove the unused themes/microcks/package.json
• remove the corresponding unused themes/microcks/package-lock.json
• retain the root Node manifests as the single dependency definition used by Hugo and Netlify

The nested manifests are leftover theme-scaffold metadata. Their scripts reference an absent exampleSite, and neither the root Netlify build nor deploy.sh installs dependencies from themes/microcks. The microcks.github.io repository receives only the generated public output.

Removing them also prevents duplicate Dependabot updates for a dependency tree that is not installed. Related obsolete PRs #563, #527 and #523 have been closed.

Verification

• npm run build
• production Hugo build completed successfully: 214 pages and 1,802 processed images
• git diff --check
• confirmed the PR contains only the two manifest deletions

Closes #575