Micromark Normalize Identifier Utility

micromark-util-normalize-identifier is a dedicated utility package within the `micromark` ecosystem, designed to provide a robust algorithm for normalizing identifiers encountered in markdown, such as those in references and definitions. The current stable version is `2.0.1`, which is compatible with `micromark@3` and requires Node.js 16 or later. As part of the actively developed `micromark` monorepo, it follows a release cadence tied to the broader project's updates. Its key differentiator lies in its specific approach to canonicalizing identifiers: it collapses markdown whitespace, trims, and then performs a precise lower- and uppercase transformation. This two-step case conversion addresses edge cases with certain Unicode characters (e.g., U+03F4 vs. U+03B8 vs. U+0398) to ensure a truly canonical form, while also using uppercase last to prevent collisions with `Object.prototype` properties like `constructor`. It is an ESM-only package.