Consider specialized fungible asset delta tracking

I was thinking more about reducing the number of cycles as we could maybe do something clever with the amounts - like:

```
let delta = final - initial
let is_negative = delta < 0
let delta_op = is_negative + 1
let amount_delta = delta * (1 - 2 * is_negative)
```

But I'm actually not sure how much this is saving. We can leave things as is and create an issue to investigate this optimization later.

_Originally posted by @bobbinth in https://github.com/0xMiden/protocol/pull/3038#discussion_r3391667005_