Fix: Embed GitHub videos in docs site (remark plugin)

[rstrahan]

Problem

GitHub video URLs (e.g. https://github.com/user-attachments/assets/<id>) render as inline video players on GitHub, but appear as plain text links on the Starlight docs site.

Before: https://aws-solutions-library-samples.github.io/accelerated-intelligent-document-processing-on-aws/demo-videos/ showed 21 video URLs as text links

After: All 21 videos render as embedded <video> players with play controls, matching GitHub's native behavior

Solution

Added a custom remark plugin (docs-site/plugins/remark-github-video.mjs, ~50 lines) that:

1. Walks the markdown AST during Astro's build
2. Finds paragraphs containing a single bare github.com/user-attachments/assets/ URL
3. Replaces them with <video controls> HTML elements

Key properties:

• No changes to any docs/*.md files — the markdown continues working on GitHub exactly as before
• Automatic — any future GitHub video URLs in any doc will also be embedded
• Zero new npm dependencies — uses remark's built-in AST visitor pattern

Files changed

File	Change
docs-site/plugins/remark-github-video.mjs	New — remark plugin
docs-site/astro.config.mjs	Register the remark plugin
docs-site/src/styles/custom.css	Video element styling
docs-site/package.json	Pin zod@3 (fix Starlight build compat)

Verification

Built and deployed to GitHub Pages — 21 video tags confirmed in dist/demo-videos/index.html.