fix: stop distribute() from looping forever on a non-positive count

[spokodev]

Problem

distribute(count) loops with for (; count !== 0; count--), which only reaches 0 for a positive integer count. A negative or fractional count decrements past 0 forever, pushing currency objects into the result array until the process runs out of memory:

const currency = require('currency.js');

currency(1).distribute(-1);   // never returns -> FATAL ERROR: heap out of memory
currency(1).distribute(2.5);  // never returns -> FATAL ERROR: heap out of memory

count is part of the public, number-typed API (distribute(count: number)), so a caller-supplied (e.g. user-controlled) value can hang and crash the process. distribute(0) already returns [], so the positive-integer assumption is only implicit.

Fix

Bound the loop with for (let i = 0; i < count; i++) so it always terminates. A non-positive count now yields an empty distribution (consistent with distribute(0)), and positive-integer counts behave exactly as before (the loop body never referenced count).

Test

Added a test asserting distribute(0) and distribute(-1) return [] instead of looping forever. The full suite passes (63 tests).