This update adds the ability to control which actions appear in the dropdown menu via the enabledActions configuration option. This is particularly useful for private documentation sites where AI tool links (ChatGPT/Claude) won't work due to inaccessible URLs.

Features:
- New enabledActions option to show/hide specific dropdown actions
- Available actions: 'copy', 'view', 'chatgpt', 'claude'
- Default behavior unchanged: all actions enabled
- Fully backward compatible

Example usage:
```
plugins: [
  [
    "docusaurus-plugin-copy-page-button",
    {
      enabledActions: ['copy', 'view'], // Hide AI tool buttons
    },
  ],
],
```

Closes #2