LMFit.convert_to_pars_obj crashes: Parameters.add_many takes varargs, not a list

[rozyczko]

Finding F-H3 in DEEP_ANALYSIS.md (parent #261). Verified against installed lmfit.

minimizer_lmfit.py:271-274:

lm_parameters = LMParameters().add_many([
    self.convert_to_par_object(parameter) for parameter in parameters
])

add_many(*parlist) takes varargs; passing one list makes lmfit do Parameter(*[LMParameter, ...]) -> TypeError: unhashable type: 'Parameter'. Even with * unpacking, add_many returns None, so the return value is wrong either way. Fitter.convert_to_pars_obj is therefore broken for the default minimizer family; the unit test passes only because it mocks the minimizer.