[scripts] Clarify POMM peak report workflow naming

[Chain-Frost]

Summary

• rename the shared POMM peak report workflow to generate_peak_report and expose clearer export_mean_peak_report / export_median_peak_report helpers while keeping the legacy entry points available
• update the POMM wrappers to call the new helper names and mark deprecated interfaces
• clarify the mean peak metadata descriptions and ensure nearest-to-mean defaults surface as NaN

Testing

• pytest tests/functions/test_median_calc.py (fails: ModuleNotFoundError: No module named 'ryan_library'; repository is not installed as a package in the test environment)

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