d585ab425c
- Add `npm` package type to config with no built-in mutable defaults; users set explicit mutable_patterns (e.g. ^(?!.*\.tgz$).*) and immutable_patterns (e.g. \.tgz$) in remotes.yaml - Rewrite dist.tarball URLs in metadata JSON on the fly so tarball downloads pass through the same proxy remote instead of hitting npmjs.org directly - Single-remote design: npm_files_remote points back to itself since both metadata and tarballs are served from registry.npmjs.org - Add .tgz to _get_content_type (application/gzip) - Add example npm remote to remotes.yaml - Add npm proxy section to README covering remotes.yaml config, client setup (npm/yarn/pnpm), rewriting behaviour, and mutable vs immutable path table - Add tests for mutable pattern matching, URL rewriting, content-type, scoped packages, cache miss, and tarball immutability