chore: add standalone iTunes catalog evaluation CLI

[amitbreuer]

Summary

• Add a dependency-free Node.js CLI for public iTunes text search, numeric track lookup, and Apple Music song-link lookup.
• Support readable and complete JSON output, storefront selection, bounded search limits, input validation and timed requests.
• Document usage and catalog limitations. No API key or paid Apple membership is required.

Validation reported by implementation session

• 12 automated tests passed.
• Two live public read-only requests returned four search results and one exact lookup for Get Lucky (track ID 617154366).

Scope

Only README.md, scripts/itunes-search.mjs and tests/itunes-search.test.mjs changed. No Party integration, Spotify requests, cloud changes or production refactor.

The iTunes catalog is not the complete Apple Music catalog and these results do not provide ISRCs. This tool is for evaluating examples before deciding whether to change the production metadata adapter.