Lazy-loaded images are rendered with their data: placeholder instead of the real image #88

Lazy-loaded images are rendered with their placeholder src rather than the real image.

Observed

On a Wayback Machine capture of https://www.benjerry.com/flavors/flavor-graveyard (web.archive.org/web/20230129141559/…), most images in the dump came out as:

[![Dastardly Mash](data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==) Dastardly Mash](…)

That data: URI is the usual 1×1 transparent GIF lazy-loading libraries put in src until the image scrolls into view.
The real URL sits in another attribute (typically data-src, data-lazy-src, data-original, or srcset/data-srcset).

Why it matters

• The Markdown carries ~80 bytes of noise per image and none of the information, so a model can neither see nor fetch the image.
  In this case the photos were what the task needed, and the agent had to go through each flavor page instead.
• A dump is taken without scrolling, so on a lazy-loading page this hits nearly every image below the fold.

Suggested behaviour

When src is a data: URI (or missing), fall back in this order:

1. currentSrc, if the element has already resolved one;
2. data-src / data-lazy-src / data-original;
3. the best candidate of srcset / data-srcset.

If nothing better exists, emit the image without a data: placeholder (alt text only) rather than inlining the placeholder.