Fix the convergence check being skipped when verbose=True

[jacobdparker]

The convergence test in MartInverter.__call__ was an elif chained behind the verbose print statement:

if verbose:  # pragma: nocover
    print(f"merit: {merit}")

elif (merit_old - merit) < self.threshold_convergence:
    ...
    break

so any run with verbose output could never stop at the convergence threshold and always ran to num_iteration (with the max-iterations warning). Found while running MART inversions of the ESIS-I flight data, where verbose runs always burned the full iteration budget.

This splits the check into an independent if, and adds a regression test that inverts with verbose=True and asserts early convergence — the test fails on the previous code.

🤖 Generated with Claude Code

https://claude.ai/code/session_01HuYXL1BkWsWGAxYnpD8Kqz

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (2eb14d0) to head (d952619).

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #21   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           23        23           
  Lines          697       702    +5     
=========================================
+ Hits           697       702    +5     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

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