fix(prover): adds a padding pragma for the mimc code hash module

[AlexandreBelling]

This PR implements issue(s) #

Checklist

• I wrote new tests for my new core changes.
• I have successfully ran tests, style checker and build against my new changes locally.
• I have informed the team of any breaking changes if there are any.

---

Note

Mark mh.IsActive as right-padded in the MiMC code hash module by adding a padding pragma before column assignment.

^{Written by Cursor Bugbot for commit 5865dc5. This will update automatically on new commits. Configure here.}

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.38%. Comparing base (85bf84e) to head (5865dc5).

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #1733   +/-   ##
=========================================
  Coverage     65.38%   65.38%           
  Complexity     1491     1491           
=========================================
  Files           385      385           
  Lines         14005    14005           
  Branches       1450     1450           
=========================================
  Hits           9157     9157           
  Misses         4240     4240           
  Partials        608      608           

Flag	Coverage Δ		*Carryforward flag
hardhat	96.20% <ø> (ø)
kotlin	62.94% <ø> (ø)		Carriedforward from 85bf84e

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