Convert repo into consumable npm package

[fntn]

This pull request introduces npm packaging support for the repository, enabling seamless integration with JavaScript/TypeScript applications. It adds a build system to auto-generate distributable modules, documentation for npm usage, and updates the repository metadata to reflect its new capabilities.

NPM Packaging Enablement:

• Added a package.json file to define the npm package, including entry points, exports, included files, build scripts, and metadata for publishing as @cloudsmith/rego-recipes.
• Introduced a build script (scripts/build.js) that scans all .rego policy files, extracts metadata, and generates both dist/index.js (JavaScript module) and dist/index.d.ts (TypeScript definitions) for consumption as an npm package.

Documentation Updates:

• Added a new NPM.md file with detailed installation instructions, usage examples, available exports, and TypeScript type definitions for consumers of the npm package.
• Updated the README.md to reference npm usage and the new documentation, making it clear how to consume the repository as an npm package.