READ FIRST — v098 MOBILE READABILITY FIX

Purpose:
- Make /beta and other public directory listings readable on iPhone without pinch zoom.
- Keep sortable headers touchable without making the visible text freakishly large.

Rules implemented:
- Adds a real mobile viewport:
  <meta name="viewport" content="width=device-width, initial-scale=1">
- Sets a normal readable base body font size.
- Keeps sortable header text at normal inherited table size.
- Keeps an iPhone-friendly 44px minimum tap target around sortable headers.
- Keeps directory/file links easier to touch on coarse-pointer devices.
- Uses horizontal scrolling for wide directory tables instead of shrinking the page.

This is the Lambda@Edge directory-browser code, not the S3 index updater.
Replace the online 8k-art-directory-browser index.mjs with:
  s3-cloudfront-indexer/lambda-edge-directory-browser/index.mjs

After replacing:
1. Deploy the Lambda code.
2. Publish a new Lambda version.
3. Point the live alias at the new version.
4. Update the CloudFront Lambda@Edge association if needed.
5. Wait for CloudFront deployment.
6. Test https://8k.art/beta/ and https://8k.art/beta/s3-cloudfront-indexer/ on desktop and iPhone.