[JS] Remove extra files from package

[juharris]

Make the package smaller.

Fix CI issues:
rust-lang/rust#131477
The PR doesn't directly mention undefined N-API symbols. But the fact that the runner image updated Rust from 1.90 to 1.91,
and that's when the linking failures started, is compelling evidence. The fix I added (the -undefined dynamic_lookup flags) is
the correct solution regardless - it's been the standard approach for N-API addons on macOS for years.

Why the linker flags are now needed:

1. GitHub Actions runner image update: The macos-15-arm64 runner image was updated from version 20251021.0066 (used in Oct 26
   successful build) to 20251104.0104 (used in Nov 7 failed builds)
2. Rust version upgrade: The runner image update included Rust 1.90.0 → 1.91.0
3. Rust 1.91 macOS linking changes: Rust 1.91 Apple: Always pass SDK root when linking with cc, and pass it via SDKROOT env var rust-lang/rust#131477 via the SDKROOT environment
   variable. This appears to have made the linker stricter about undefined symbols in cdylibs.
4. The fix: Adding -undefined dynamic_lookup linker flags for macOS targets is the standard solution for N-API native addons,
   as these symbols are intentionally undefined and resolved at runtime by Node.js. The flags tell the macOS linker to allow
   these undefined symbols.