Handle negative numbers in bigint conversion (#425)

* Handle negative numbers in bigint conversion

* Add the exact case from issue

Author: krokosik

src/tests/number.test.ts

@@ -117,6 +117,7 @@ describe('getCurrencyHelpers', () => {
     it.each([
       ['-123.45', -12345n],
       ['-0.99', -99n],
+      ['-100.01', -10001n],
       ['-1000', -100000n],
       ['-1000.5', -100050n],