Training slides: Remove nocache directive and sanitize custom URLs

[nrichers]

Pull Request Description

What and why?

Applies fixes from #1192 (merged to prod) to main, plus an additional improvement:

1. Remove nocache directive — Replaces the nocache query parameter approach with location.reload(true) to fix odd behavior observed in the training login slides.
2. Strip trailing slashes — Sanitizes custom URL input to prevent issues with URL replacement when users enter URLs with trailing slashes with can lead to iframed 404s.

How to test

1. In the preview, open a training module with the "Before you begin" login tab.
2. Click "Custom URL" and enter a URL with trailing slashes (example: https://app.dev.vm.validmind.ai/).
3. Click "Save & Reload" and verify the trailing slash is stripped.
4. Check that custom URLs get rendered correctly on some iframed pages.

Before	After
URLs can end in /: Which can lead to 404s due to a double //:	URLs are sanitized to strip the /: Which renders as expected:

What needs special review?

N/A — straightforward changes already validated in prod.

Dependencies, breaking changes, and deployment notes

None.

Release notes

N/A — internal fix.

Checklist

• What and why
• Screenshots or videos (Frontend)
• How to test
• What needs special review
• Dependencies, breaking changes, and deployment notes
• Labels applied
• PR linked to Shortcut
• Unit tests added (Backend)
• Tested locally
• Documentation updated (if required)
• Environment variable additions/changes documented (if required)

[github-actions]

PR Summary

This PR introduces two key enhancements:

1. In the vmurl-settings.js file, the function that saves a custom URL to localStorage has been updated to trim any trailing slashes. This ensures that URLs are stored in a consistent format by removing extra trailing slashes using a regex.

2. In the _log-in-with-jupyterhub.qmd and _log-in.qmd files, the refresh button behavior has been modified. Instead of constructing a new URL with a cache-busting query parameter, the button now triggers a full page reload using location.reload(true). This change simplifies the refresh mechanism and ensures that the latest content is fetched from the server.

Test Suggestions

• Verify that when a URL with trailing slashes is saved, the stored value in localStorage does not include the trailing slashes.
• Test the refresh button on both login pages to confirm that clicking it performs a full page reload and properly fetches the latest content.
• Check edge cases such as providing empty or whitespace-only inputs to ensure the URL is removed from localStorage as expected.

[github-actions]

Lighthouse check results

⚠️ WARN: Average accessibility score is 0.87 (required: >0.9) — Check the workflow run

Show Lighthouse scores

Folder depth level checked: 0

Commit SHA: 7d6a626

Modify the workflow to check a different depth:

• 0: Top-level navigation only — /index.html, /guide/guides.html, ...
• 1: All first-level subdirectories — /guide/.html, /developer/.html, ...
• 2: All second-level subdirectories — /guide/attestation/*.html, ...

Page	Accessibility	Performance	Best Practices	SEO
/developer/validmind-library.html	0.85	0.65	1.00	0.82
/get-started/get-started.html	0.85	0.74	1.00	0.73
/guide/guides.html	0.85	0.69	1.00	0.82
/index.html	0.93	0.69	1.00	0.82
/releases/all-releases.html	0.86	0.69	1.00	0.73
/support/support.html	0.91	0.68	1.00	0.82
/training/training.html	0.85	0.69	0.96	0.73

[github-actions]

Validate docs site

✓ INFO: A live preview of the docs site is available — Open the preview

[validbeck]

This seems to work as expected, as far as I can tell.