feat(preimage-proof): feat(preimage-proof): implement preimage proof …

[sumitvekariya]

Description

This PR implements a preimage proof circuit that allows proving knowledge of a hash preimage without revealing it. This circuit is a fundamental building block for many zero-knowledge proof applications, enabling users to prove they know a value that hashes to a specific result without disclosing the original value.

Key features of this implementation:

• Simple and easy-to-use API with just two main functions:
  • prove_field for proving knowledge of Field element preimages
  • prove_bytes32 for proving knowledge of 32-byte array preimages
• Flexible design that works with any hash function that matches the required signature
• Comprehensive documentation with usage examples
• Test suite covering both Field elements (with mock Poseidon hash) and byte arrays (with mock SHA-256 hash)

This implementation avoids using complex generic trait bounds which were causing compilation errors with Noir's current capabilities, opting instead for a simpler and more reliable approach with specific function implementations.

Related Issue(s)

Fixes #45

Checklist

• I have read and understand the contributor guidelines and code of conduct.
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have run bun check without getting any errors (Note: Will run locally before final PR submission)
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes