Description

Security Fix: Replaced unsafe bit shift operation with proper SNARK scalar field reduction in packages/proof/src/hash.ts.

Problem

The hash function was using >> 8n bit shift which discards 8 least significant bits of the keccak256 hash, significantly reducing cryptographic entropy and increasing collision risk.

Solution

• Replaced bit shift with modular arithmetic using SNARK scalar field modulus
• Preserves full hash entropy (256 bits → 248 bits was unsafe)
• Maintains SNARK compatibility with proper field reduction
• Eliminates collision risk from entropy loss