Replace the unmaintained @pnpm/npm-conf package with a purpose-built
module that reads only auth/registry-related settings from .npmrc files
using read-ini-file + @pnpm/config.env-replace (both already deps).
All non-registry settings (hoist-pattern, node-linker, etc.) are now
only read from pnpm-workspace.yaml, CLI options, or environment
variables. Registry-related settings (auth tokens, registry URLs,
SSL certs, proxy settings) continue to be read from .npmrc for
migration compatibility, and can also be set in pnpm-workspace.yaml.
New modules:
- loadNpmrcFiles.ts: reads .npmrc from standard locations, filters to
auth/registry keys, returns structured layers
- npmConfigTypes.ts: inlined npm config type definitions
- npmDefaults.ts: inlined npm defaults (registry, unsafe-perm, etc.)