Feat/dual int64 18 18 precision#31

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PKartaviy wants to merge 12 commits intorobaho:masterfrom

PKartaviy:feat/dual-int64-18-18-precision

Commits on Feb 18, 2026

Implement zero-allocation Div using base-10^9 long division (Knuth Algorithm D)

PKartaviy
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claude
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Commits on Feb 23, 2026

use more precise ipow10. Explicitly process errors
PKartaviy
committed
Optimize tostr() to zero-allocation using stack byte buffer

PKartaviy
and
claude
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Add thorough tests for tostr() and MarshalJSON benchmark

PKartaviy
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claude
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