Strengthen defensive checks

[Fantoni0]

After #434, we changed how we build inputs and how we compile circuits.
For now, missing or short inputs are padded with zeroes and get accepted in the proofs. The proofs will fail later, but it would be nice to reject them at the witness-building phase.

[Y0sefTamer]

Hi @Fantoni0,

I worked on this issue!

Based on the description, my approach to update compute_witness to apply a fail-fast mechanism during the witness-building phase. I planed to:

Check if the provided inputs are missing by comparing the length of the parsed inputs to self.input_hashes.len().

Change the length validation inside the loop from values.len() > expected_size to values.len() != expected_size to ensure we reject short inputs instead of zero-padding them.

Let me know if this sounds good to you, and please assign this issue to me if it's still available!