Add INpmRegistryPackageResponse and INpmRegistryVersionMetadata interfaces
to support the upcoming replacement of the package-json dependency with a
local implementation using WebClient.

- INpmRegistryVersionMetadata extends INpmCheckPackageVersion for backward
  compatibility
- INpmRegistryPackageResponse models the full npm registry API response
- Added JSDoc with links to npm registry API documentation

…data

Implement NpmRegistryClient class to replace external package-json dependency
with a self-contained HTTP client using Node.js built-in modules.

Features:
- INpmRegistryClientOptions for configuring registry URL, user agent, timeout
- INpmRegistryClientResult for consistent error handling
- Automatic scoped package URL encoding (@scope/name -> @scope%2Fname)
- Support for gzip/deflate response decompression
- Proper error handling for 404, HTTP errors, network errors, and timeouts

Replace package-json and throat dependencies with NpmRegistryClient for
fetching npm registry metadata. Preserves existing version sorting and
homepage extraction logic.

Changes:
- Remove package-json and throat imports
- Add lazy-initialized module-level NpmRegistryClient instance
- Update getNpmInfo to use fetchPackageMetadataAsync
- Preserve lodash/semver version sorting
- Preserve bestGuessHomepage extraction

…hing

Add batch fetching function to retrieve metadata for multiple packages
concurrently with configurable concurrency limit.

Features:
- getNpmInfoBatch(packageNames, concurrency) returns Map<string, INpmRegistryInfo>
- Default concurrency matches CPU count (like original throat behavior)
- Processes packages in batches using Promise.all

Remove external dependencies that have been replaced by NpmRegistryClient:
- package-json: replaced by NpmRegistryClient
- throat: replaced by Promise.all batch processing

Update tests to mock NpmRegistryClient instead of package-json.

Add basic unit tests for NpmRegistryClient constructor options.
Update GetLatestFromRegistry tests with improved module mocking.

Document the removal of package-json and throat dependencies in favor of
internal NpmRegistryClient implementation.