Remove the ark-circom dependency completely

[seemenkina]

Background

Currently, ark-circom is used for three primary purposes:

1. Zkey reading and parsing
2. Witness calculation
3. Groth16 proof calculation

Current Status

• We've already switched to calculating proofs using iden3
• Key parsing can be accomplished with alternative libraries. For now use ark-zkey approach, but it requires changes
• Witness calculation still needs to be addressed (example of usage:

  zerokit/rln/src/protocol.rs

  Lines 562 to 570 in 8a3e33b

  	let proof = Groth16::<_, CircomReduction>::create_proof_with_reduction_and_matrices(
  	&proving_key.0,
  	r,
  	s,
  	&proving_key.1,
  	proving_key.1.num_instance_variables,
  	proving_key.1.num_constraints,
  	full_assignment.as_slice(),
  	)?;

Why Remove ark-circom?

The dependency introduces significant compatibility issues:

• We can't use version 0.1.0 due to outdated dependencies
• We can't use version 0.5.0 because it conflicts with newer versions of other ark libraries
• Our current approach (using master branch with loosened dependencies) depends on wasmer-wasix which lacks x32 system support. See their open issue : wasmer-wasix fails to compile on arm and armv7 linux builds wasmerio/wasmer#4227

Proposed Solution

Replace all remaining ark-circom functionality with alternative implementations:

• Witness calculation: Already migrated to iden3 (see Replace the ark-zkey witness calculator with the one of iden3 #273)
• Key parsing: Research and implement alternative libraries
• Proof calculation: Identify and implement replacement