Generate a validated format-1 plugin market index from a list of npm package
names and https Git repository URLs, without running package code.
- List every non-deprecated npm bundle version, and Git versions at release
tags and the default branch, each with its engines.dsh range.
- Read display fields, keywords, homepage, and icons the way DSH reads
installed plugins; inline small icons up to the format's 32 KiB limit.
- Cache results per immutable input and rewrite output only when it changes.