feat: add WrappingArithmetic trait, include in LinkReference bounds, re-export num-traits

[konard]

Summary

• Added WrappingArithmetic composite trait bundling all 6 wrapping arithmetic traits from num-traits: WrappingAdd, WrappingSub, WrappingMul, WrappingNeg, WrappingShl, WrappingShr
• Added WrappingArithmetic as a supertrait of LinkReference, so downstream crates can use T: LinkReference without needing explicit + WrappingAdd bounds
• Re-exported all num-traits traits used in supertraits (PrimInt, AsPrimitive, ToPrimitive, FromPrimitive, Unsigned, Signed, and all 6 Wrapping* traits), so downstream crates can drop their direct num-traits dependency entirely

Motivation

After removing LinkType from platform-data (data-rs#16, data-rs#17), WrappingAdd is needed for wrapping unsigned arithmetic in Hybrid (internal/external link reference encoding). Currently data-rs must add num-traits as an explicit dependency and write T: LinkReference + WrappingAdd everywhere. With this change, T: LinkReference is sufficient.

The re-exports also address #141: downstream crates (data-rs, tree-rs, doublets-rs) can now import all needed num-traits directly from platform-num, eliminating version drift risk.

Design decisions

• WrappingArithmetic name: The maintainer disliked WrappingAdd as a name to add directly. After researching num-traits, there is no existing composite wrapping trait. WrappingArithmetic bundles all 6 wrapping ops and follows the same composite pattern as Number (which bundles PrimInt + Default + Debug + AsPrimitive<usize> + ToPrimitive)
• All 6 wrapping traits included: Not just WrappingAdd — includes WrappingSub, WrappingMul, WrappingNeg, WrappingShl, WrappingShr since all are implemented for all unsigned integer types
• Compatible addition: All types that implement LinkReference (u8, u16, u32, u64, u128, usize) already implement all 6 wrapping traits
• Re-exports: All num-traits traits that appear as supertraits in this crate are re-exported, following the pattern requested in Re-export num-traits traits (Unsigned, FromPrimitive) to allow dependents to remove direct num-traits dependency #141

Changes

File	Change
rust/src/imp.rs	New WrappingArithmetic trait + added as LinkReference supertrait
rust/src/lib.rs	Export WrappingArithmetic, re-export all num-traits, updated docs table
rust/tests/traits.rs	16 new tests for wrapping arithmetic
changelog.d/	Changelog entry (bump: minor)
docs/case-studies/issue-146/	Case study analysis with raw data
experiments/	Verification scripts

Test plan

• cargo build compiles cleanly
• cargo fmt --all -- --check — no formatting issues
• cargo clippy --all-targets — zero warnings
• cargo test — 112 unit tests + 7 doc tests pass (was 96 + 6)
• Verified all 6 wrapping traits implemented for u8, u16, u32, u64, u128, usize
• CI pipeline passes (all jobs green)

Closes #146
Also addresses #141

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[konard]

🤖 Solution Draft Log

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[konard]

✅ Ready to merge

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[konard]

I think as in #141 we should reexport all related num traites we inherited from num traites library and that can be useful for the users of our library, so there is no problems with synchronization of num traites library, and all data-rs, tree-rs and doublets-rs will be able to just drop the import of num traits directly.

[konard]

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[konard]

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💰 Cost: $1.583205

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Total: (42.4K + 2.2M cached) input tokens, 9.2K output tokens, $1.583205 cost

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[konard]

✅ Ready to merge

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