hast-util-excerpt: HTML Tree Excerpt Utility

hast-util-excerpt is a utility within the unified (specifically hast/rehype) ecosystem designed to truncate an HTML (hast) syntax tree based on an explicit comment marker, typically `<!--more-->`. This allows authors to precisely define where a document's 'excerpt' or 'summary' should end, offering more control than character-count-based truncation methods. The current stable version is 2.0.0, which introduced significant breaking changes by moving to ESM-only and requiring Node.js 16 or newer. Releases occur as changes accumulate, rather than on a fixed schedule. Its primary differentiator is the author-defined explicit truncation point, making it suitable for content management systems or static site generators where content creators need fine-grained control over document summaries. It works by traversing the tree and stopping at the specified comment, returning a modified clone of the original tree.