Optimize bigint division for fast path

[vigneshakaviki]

Summary

• Optimized bigint division when lhs.numDigits < rhs.numDigits
• Avoids expensive tcDivide computation for common case
• Performance: O(n) instead of O(n²) for this case

Changes

• Added fast-path check in div_rem::compute()
• When dividend has fewer digits than divisor, quotient is 0 and remainder is lhs
• Directly sets results without calling expensive tcDivide

Performance Impact

• Significant speedup for bigint divisions where dividend < divisor
• Eliminates allocation and computation overhead
• Common operation in JavaScript number handling

Test Plan

• Fast path produces correct quotient (0) and remainder (lhs)
• Works for both positive and negative numbers
• Existing division tests continue to pass

[meta-cla]

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