Replace kilic/bls12-381 with gnark-crypto in Wallet

[b00f]

Description:

The wallet currently uses kilic/bls12-381 for BLS signatures, while the rest of the software relies on gnark-crypto.
To ensure consistency, maintainability, and reduce reliance on unmaintained libraries, the wallet should also migrate to gnark-crypto.

Since the existing tests do not depend on kilic/bls12-381 internally, no test updates are expected during this migration.

Tasks:

1. Replace all kilic/bls12-381 usages in the wallet with gnark-crypto.
2. Verify functionality with existing tests.
3. Test the wallet on both 32-bit and 64-bit systems.

Related Issue: #1565