Add Xquik add-on bundle

[kriptoburak]

Summary

• Add a skill-only Xquik add-on bundle for read-only X data research workflows.
• Register the bundle in registry/add-ons.json.
• Scope the workflow to public REST paths for tweets, users, trends, and radar.
• Keep write actions outside the default behavior.

Validation

• npm run test:bundle-contract
• Crow registry check mode
• jq empty bundles/xquik/manifest.json registry/add-ons.json
• https://xquik.com/openapi.json returned 200
• https://xquik.com returned 200