The return value of index.count() was a boolean, so it was changed to a number.

For example, if you try to add the same key, it aborts.

```
terminate called after throwing an instance of 'std::runtime_error'
  what():  Duplicate keys not allowed in high-level wrappers
Aborted (core dumped)
```

Improved error handling to throw JavaScript exceptions.

I got an error when I loaded and searched with load() or view().

Code Example:

```js
// Saved with `index.save('index.usearch');` in another script.
index.load('index.usearch');
const results = index.search(new Float32Array([0.2, 0.6, 0.4]), 10);
```

The test itself succeeds, but fails with the following error when deleting the index file created by save() in afterEach().

```
error: "EBUSY: resource busy or locked, unlink 'C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\usearch.test.index'"
```

Since it is only in Winodws that it fails, we will skip it on Winodws for now.
We will continue to investigate the solution.

Add Rust and Android CI build

The index read by `view()` is read-only.
When I did a `remove()` on that index, it crashed.

---------

Co-authored-by: Ash Vardanian <1983160+ashvardanian@users.noreply.github.com>

---------

Co-authored-by: Mikhail Bautin <mbautin@users.noreply.github.com>