Convert Simon Willison's blog content into a formatted newsletter ready for Substack by pulling entries, links, quotes, and other content from the past several days. The tool fetches data from a Datasette backup of simonwillison.net and allows you to customize the newsletter by selecting which items to include, reordering stories, and detecting overly long URLs that may need shortening. You can copy the generated HTML directly into Substack or export just the links and supplementary content separately.