Implement Responsive Table of Contents (TOC) for Mobile View

[freedeaths]

Is your feature request related to a problem? Please describe.
The current mobile version of Perlite lacks a Table of Contents (TOC) feature, which is available on the desktop version. This absence makes it difficult for mobile users to navigate through long documents efficiently, as they can only scroll through the content without any quick navigation options.

Describe the solution you'd like
Implement a TOC feature for the mobile version of Perlite. This could be in the form of a floating button or any other suitable format. When activated, it should display the TOC, allowing users to quickly jump to specific sections of the document. The TOC should be hidden by default and only appear when needed to maintain a clean reading experience.

Describe alternatives you've considered

1. A collapsible sidebar that contains the TOC.
2. A dropdown menu in the top navigation bar that shows the TOC when tapped.
3. A floating button that expands to show the TOC when tapped, similar to a "scroll to top" button.

Additional context
This feature is crucial for improving the user experience on mobile devices, especially for longer documents. It would bring the mobile functionality closer to parity with the desktop version, ensuring that mobile users can navigate content as efficiently as desktop users.