feat: Cairo spending conditions

[YofiY]

Description

This PR implements Cairo Speding condition as specified in NUTXX for cashu tokens, enabling privacy-preserving arbitrary spending conditions through zero-knowledge proofs.

Features:

• Sending Cairo-locked token:

  • Creation of the Cairo secret type
  • Executable program hashing with blake2S
  • Minimal Implementation of the Felt252
  • Integration of the sending workflow in the CashuWallet

• Receiving Cairo-locked tokens:

  • Integration of the WASM64 compiled stwo-cairo prover from the stwo-cairo-ts library
  • Integration of receiving workflow in the CashuWallet

• Integration tests that run for the the NUTXX-supporting rust mint

• Unit tests for the helper functions

Note to the reader

• To support the cairo prover, make sure to have your server set the correct security headers