Fix duplicated variable in baseline noise check

[robertyoung3]

Summary

• MassSpecBase.plot_mz_domain_profile() (line 1094) checks self.baseline_noise_std twice instead of checking self.baseline_noise and self.baseline_noise_std
• Changed from truthiness check to is not None so valid 0.0 values are not incorrectly treated as missing

Before

if self.baseline_noise_std and self.baseline_noise_std:

After

if self.baseline_noise is not None and self.baseline_noise_std is not None:

Test plan

• Verified the fix matches the intended logic by inspecting surrounding code (line 1096 uses self.baseline_noise)
• One-line change, no behavioral impact except correcting the None/zero handling

[kheal]

Hi @robertyoung3, thanks for putting in this PR.

Generally speaking, the requested functionality change / bug fix looks good.

However, we don't want to add the extraneous changes (the .claude/, .devcontainer/, openspec/, changes to docker- etc) in this PR. Could you cull this PR to the minimum diff changes needed to repair the functionality you've described? Essentially just the change in MassSpectrumClasses.py module. We'd want this for the other PRs you've put in as well (#26, #27, #28, #29).

Thanks in advance!

[robertyoung3]

Hi Katherine,
Sorry about that! The PRs have been culled to the minimum diff changes, and I'll keep it that way in the future.
Cheers,
Robert