tsdown: The Elegant Library Bundler

tsdown is a blazing-fast bundler for JavaScript and TypeScript libraries, leveraging the Rust-based Rolldown engine. It's designed for simplicity and efficiency, preconfiguring most settings to allow developers to focus on code. The current stable version is `0.21.9`, with frequent minor releases as seen in its active changelog. Key differentiators include its speed (powered by Oxc and Rolldown), a powerful ecosystem supporting Rolldown, Rollup, Unplugin, and some Vite plugins, and a focus on seamless migration for `tsup` users by offering compatible options and features. It also provides automatic TypeScript declaration generation, multiple output formats (esm, cjs, iife, umd), and built-in support for features like CSS handling and executable bundling.