cron() accepts non-ASCII digits that BusyBox cron rejects

On current master (22786cc), cron("٣٠ 3 * * *") returns True. BusyBox cron 1.37.0 rejects that minute field. The same mismatch affects the other fields, ranges, lists and steps.

I have a focused fix ready with 11 regression cases. All 1,585 tests pass on each of Python 3.11–3.14 on Windows; formatting, lint and type checks also pass.

Would you fund a focused PR for 25 USDC on Base?