kaidokert / fixed-bigint-rs / 29697842029

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main: 97%

Pull #157

github

Implement num_integer::Integer for HeaplessBigInt

The last Tier-1 parity item — gcd/lcm/div_floor/mod_floor/divides/
is_multiple_of/is_even/is_odd/div_rem, Nct-only, mirroring FixedUInt.

- div_floor/mod_floor/div_rem: the unsigned div/rem (floor == truncating).
- gcd: Stein's binary algorithm. Heapless `>>` narrows `len`, so the running
  values shrink — value-correct (comparisons are value-based), but the result
  is pinned to the operand width max(len): widen before the final `<< shift`
  so no bit is lost and the width matches FixedUInt<k>. Dedicated
  heapless-internal test for the sub-capacity width case.
- lcm = a / gcd(a, b) * b; is_even/is_odd: O(1) LSB check like FixedUInt.

Tests: generic gcd/lcm/div/parity for both carriers (carrier_num_traits) plus
heapless-internal gcd width-preservation and multi-limb gcd/lcm.

Tier-1 parity is now complete: HeaplessBigInt<_, Nct> is a drop-in
num_traits::PrimInt + num_integer::Integer.

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