Remove Jekyll workflow and fix npm publish hooks

- Remove .github/workflows/jekyll.yml
  - Stop building/deploying Jekyll site via GitHub Pages
  - Keeping publish-npm.yml and update-mcp-package.yml workflows

- Fix mcp-package/dist/package.json
  - Remove build and prepublishOnly scripts that reference non-existent build.js
  - Allows npm publish:npm to succeed without errors

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Co-Authored-By: Claude <noreply@anthropic.com>

Author: theodorosploumis