Include github-markdown-css locally to support offline environments

[Jaguar-Kwok]

I am using Terrakube in an air-gapped/offline environment, and I noticed that the current implementation relies on an external CDN to load the github-markdown-css stylesheet (via cdnjs.cloudflare.com). Since offline environments cannot access this CDN, the styling for markdown content is broken, affecting the user experience.

Proposed Solution:
To make Terrakube fully functional in offline setups, we recommend embedding the github-markdown-css CSS file directly in the project instead of using the CDN. This involves:

Adding the MIT-licensed github-markdown-css file (v4.0.0) to the repository (e.g., in the public/ directory).

Updating the HTML template to reference the local CSS file instead of the CDN URL:
ui/public/index.html
<link href="https://cdnjs.cloudflare.com/ajax/libs/github-markdown-css/4.0.0/github-markdown.min.css" rel="stylesheet">
Proposed change
<link href="%PUBLIC_URL%/github-markdown.min.css" rel="stylesheet">

Why This Matters:
This change ensures Terrakube works out-of-the-box in restricted networks without compromising functionality. Since the CSS is MIT-licensed, we can safely include it by preserving the license header in the file.

Additional Notes:
The specific version (4.0.0) can be downloaded directly from the GitHub release.

Would the team be open to a pull request implementing this change? We’re happy to contribute if this aligns with the project’s goals!

Anything else?

No response

[alfespa17]

All help is welcome @Jaguar-Kwok, you can send the pull request and I can check it later.