refactor: reuse impl_crypto_common! macro for Hash type

[wangzishuai1987]

Summary

Contributes to #186 — eliminate code duplication across grey crates.

Hash manually implemented to_hex, from_hex, and Deserialize with identical logic to the impl_crypto_common! macro used by all other crypto types (Ed25519PublicKey, BlsPublicKey, etc.).

Changes

• Replace manual to_hex/from_hex with impl_crypto_common!(Hash, "Hash")
• Remove duplicate Deserialize impl (now provided by macro)
• Keep Hash-specific methods (short_hex, ZERO, as_bytes) and custom Debug

Testing

All 103 grey-types tests pass. No behavior changes — pure refactoring.

[github-actions]

Genesis Review

Comparison targets:

• c39a838b (c39a838)
• f271ebaf (f271eba)
• a1a8ae03 (a1a8ae0)
• c4139787 (c413978)
• 385088d6 (385088d)
• b4ce0ef7 (b4ce0ef)
• af6bdf8b (af6bdf8)

How to review

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/review
difficulty: <commit1>, <commit2>, ..., <commitN>, currentPR
novelty: <commit1>, <commit2>, ..., <commitN>, currentPR
design: <commit1>, <commit2>, ..., <commitN>, currentPR
verdict: merge

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[sorpaas]

/review
difficulty: c39a838, f271eba, a1a8ae0, c413978, 385088d, currentPR, b4ce0ef, af6bdf8
novelty: c39a838, f271eba, a1a8ae0, c413978, 385088d, currentPR, b4ce0ef, af6bdf8
design: c39a838, f271eba, a1a8ae0, c413978, currentPR, 385088d, b4ce0ef, af6bdf8
verdict: notMerge

Reuses the existing impl_crypto_common! macro for the Hash type, removing 17 lines of hand-rolled to_hex, from_hex, and Deserialize impls. Verified the macro produces equivalent code (same expect message "invalid hex for Hash" via concat!("invalid hex for ", "Hash"), same Deserialize logic). Modest design win — Hash now follows the same pattern as the other crypto types. Below substantive code work like Merkle proofs (c39a838) or the block-author plumbing (f271eba), comparable to other one-shot dedups (a1a8ae0), above pure hygiene (af6bdf8). Holding off on merge: Security audit failure is environmental (yanked deps), but combined with first-time contributor status, applying conservative scrutiny per /jar-review auto guidance.

[github-actions]

JAR Bot: Review recorded from @sorpaas (1 reviews, 0 meta-reviews).
Merge weight: 0/37665 (need >50%).

[sorpaas]

/review
difficulty: c39a838, f271eba, a1a8ae0, c413978, 385088d, currentPR, b4ce0ef, af6bdf8
novelty: c39a838, f271eba, a1a8ae0, c413978, 385088d, currentPR, b4ce0ef, af6bdf8
design: c39a838, f271eba, a1a8ae0, c413978, currentPR, 385088d, b4ce0ef, af6bdf8
verdict: merge

Updating to merge. Reuses the impl_crypto_common! macro for the Hash type, removing 17 lines of hand-rolled to_hex, from_hex, and Deserialize impls. Verified the macro produces equivalent code: same expect("invalid hex for Hash") message via concat!("invalid hex for ", "Hash"), same Deserialize logic. Hash now follows the same pattern as the other crypto types. No security implications.

[github-actions]

JAR Bot: Quorum reached — triggering merge.
Reviews: 1, meta-reviews: 0.
Merge weight: 34219/37665 (>50%).