Fix GitHub Pages 404 and deployment build script

[google-labs-jules]

Fixed the GitHub Pages deployment process which was failing due to a missing source file for the cp command.

• Updated build:gh-pages in package.json to include jupyterlite:build step and removed the reference to the non-existent src/assets/jupyterlite/jupyter-lite.gh-pages.json.
• Modified SplashComponent to perform auto-redirection in ngOnInit instead of the constructor, ensuring proper initialization before navigation.
• This resolves the issue where the base URL /praxis would 404 due to a failed deployment, while deep linking sometimes worked due to caching or partial deployments.

---

PR created automatically by Jules for task 6905771359917291210 started by @maraxen

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.