Add support for `NPM_CONFIG_REGISTRY`

Editor assessment

Everything checks out. feat(npm) correctly flags a new user-facing capability, 'add support for `NPM_CONFIG_REGISTRY`' is imperative, lowercase, and names the exact environment variable in backticks, and the header sits well within the length limit. The scope matches the affected subsystem, so minor-bump inference and changelog placement will both be right. There is no body, which is acceptable for a self-explanatory flag, though a line on precedence (does it override configured registries? per-package behavior?) would make release notes more useful. As a header alone, this is close to the ideal form for a small feature.