Add Hermes Tweet plugin listing

[kriptoburak]

Summary

• add Hermes Tweet to the marketplace manifest
• include the source-native Claude plugin metadata
• add concise install notes with Hermes runtime gating

Validation

• npm run check
• npm test
• jq . .claude-plugin/marketplace.json
• jq . hermes-tweet/.claude-plugin/plugin.json
• git diff --check
• verified linked upstream README, PyPI page, Hermes Agent repo, and Xquik site return HTTP 200

License: target repo is MIT, Hermes Tweet is MIT. No existing Hermes Tweet or Xquik PRs/issues were found in this repository.