Does this fix #28621?

Yes, this is intended to fix #28621. The ZeroMQ addon failed during native addon loading because Deno did not export libuv symbols that zeromq links against, starting with uv_unref. This PR adds the missing libuv/N-API compatibility shims used by zeromq native addon initialization and covers them with N-API tests.

Intended to fix? Did you run the repro and it worked?

I reran the repro after the latest fix. It now works for the reported path:

import { Subscriber } from "npm:[email protected]";

const socket = new Subscriber();
console.log(socket.constructor.name);
socket.close();

Command used against target/debug/deno:

timeout 20s target/debug/deno run --allow-read --allow-env --allow-ffi --allow-run main.ts

Output:

Subscriber

Before the latest commit the original uv_unref lookup was gone, but the addon still failed later during initialization because napi_new_instance disallowed JS in native constructors (zeromq calls Object.seal(this)) and because uv_unref did not actually unref shimmed handles, keeping the process alive. Both are covered now.

Update PR desc and title to be more specific