fix: pick random scientific notation

[wusctong]

Resolves

Fix #160

Proposed Changes

• Updated Cast.isInt string branch to handle scientific notation: if the string contains an e, parse it numerically to check if it's truly a whole number, otherwise fall back to the dot check.
• Updated the existing test for '0.1e10' from false to true, since 0.1e10 equals 1000000000 which is a whole number.

Reason for Changes

Cast.isInt only checked for a . to decide if a string was an integer. This broke with scientific notation — 5e-1 has no dot but is 0.5 (a float), causing pick random (5e-1) to (10) to return offset values like 1.5, 3.5 instead of proper floats.

Test Coverage

Updated util_cast.js — changed cast.isInt('0.1e10') expected value from false to true, since 0.1e10 (1000000000) is a whole number and should be treated as an int.