Package URL JavaScript Library

The `packageurl-js` library provides a JavaScript implementation for parsing, constructing, and validating Package URLs (purls) according to the official purl specification (https://github.com/package-url/purl-spec). Currently at version 2.0.1, it is a microlibrary focused solely on handling purl strings and objects. It offers a `PackageURL` class for object-oriented manipulation, static methods for string parsing, and helper objects like `PurlComponent` and `PurlType` for component-level validation and normalization. Its primary differentiator is strict adherence to the purl specification, ensuring consistent and correct handling of package identifiers across different ecosystems. Given its nature as a specification implementation, release cadence is typically driven by updates to the purl specification itself or critical bug fixes.