Replace bundled AzCopy binaries with platform-specific install hook

The azcopy-node package and its platform-specific variants (azcopy-win32-x64, azcopy-darwin-arm64, etc.) bundle AzCopy binaries directly in the npm package. This is flagged as non-compliant under Foreign Checked-In Binaries (FCIB) policy.

Proposed solution

Add an install hook to azcopy-node that downloads the correct AzCopy binary for the target machine's platform and architecture at npm install time, rather than shipping pre-bundled binaries in separate packages.

Benefits

• Eliminates FCIB compliance issue — no checked-in binaries
• Removes the need for separate azcopy-{platform}-{arch} packages
• Simplifies the dependency graph

Considerations

• Install hook needs to work in CI environments (may need offline/cache support)
• Need a reliable download source for AzCopy binaries (official Microsoft CDN)
• Checksum verification of downloaded binaries
• Fallback behavior if download fails
• Air-gapped / restricted network environments

Start by locating the azcopy-node package and its azcopy-{platform}-{arch} variants, then review the npm install lifecycle and the official Microsoft CDN options. Define platform and architecture handling, checksum verification, failure and offline behavior, and confirm that installation no longer requires bundled binaries or separate platform packages.