Fix overflow detection at tolerance boundary

[google-labs-jules]

This change fixes a bug in the Balance Meter's overflow detection logic, ensuring that values exactly at the tolerance boundary are correctly flagged as overflows. The comparison operators have been updated from > to >= to include this edge case, and a new test case has been added to prevent regressions.

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PR created automatically by Jules for task 9845313514131529975

[google-labs-jules]

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