Update node import to specify index

[scotttrinh]

Trying to troubleshoot why Vite can't seem to bundle this package correct, and it looks like the built source tries to import ./node.js instead of ./node. Looks like there is a utility function that adds .js to the end of all of the imports, but this one was not updated to include the reference to the index.js that is generated.

[scotttrinh]

There is also another import that is broken: https://github.com/connor4312/blake3/blob/9195cdd08eab8226bc647b964a17bdeb7709f7f3/ts/node/hash-instance.ts#L3

In the build code, that turns into:

import { Transform } from 'stream.js';

Not sure how best to tackle that, but incorporating these two changes causes the bundle to be built successfully.