Previously, `napi_create_external_buffer` used a two-stage finalization
approach: it created the ArrayBuffer with an empty finalizer, then added
the real finalizer separately via `vm.heap.addFinalizer()`. This caused
a race condition where native code could free/reuse the underlying memory
while Bun still held a reference to the ArrayBuffer.
The fix passes the finalizer directly to `ArrayBuffer::createFromBytes`,
matching the approach already used by `napi_create_external_arraybuffer`.
This ties the cleanup correctly to the ArrayBuffer's lifecycle.
Fixes#26423
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
66a84b353d