Add massive neutrino support and improve CSV/CLI output

- Add neutrino mass parameter to SpectrumConfig and CLI interface
- Update PhaseSpace component to handle neutrino mass effects properly
- Update CSV headers to show basic endpoint and all transition types
- Add --csv-verbosity option to CLI with 'full' and 'concise' options
- Fix comparison plots to properly show linear scale variations
- Add comprehensive tests for neutrino mass functionality

beta_spectrum/nuclear_data.py

@@ -470,6 +470,7 @@ def decay_info_to_config(
     info: DecayInfo,
     e_step_MeV: float = 0.001,
     intensity_cutoff: float = 0.0,
+    neutrino_mass_MeV: float = 0.0,
 ) -> SpectrumConfig:
     """
     Convert DecayInfo to a SpectrumConfig.
@@ -482,6 +483,8 @@ def decay_info_to_config(
         Energy step size in MeV.
     intensity_cutoff : float
         Minimum branch intensity fraction to include.
+    neutrino_mass_MeV : float
+        Neutrino mass in MeV.
 
     Returns
     -------
@@ -510,6 +513,7 @@ def decay_info_to_config(
         endpoint_MeV=info.endpoint_MeV,
         transition_type=info.transition_type,
         e_step_MeV=e_step_MeV,
+        neutrino_mass_MeV=neutrino_mass_MeV,
         branches=branches,
         intensity_cutoff=intensity_cutoff,
     )
@@ -529,6 +533,7 @@ DEFAULT_JSON_SCHEMA = {
     "A_number": 99,
     "transition_type": "F2",
     "e_step_MeV": 0.001,
+    "neutrino_mass_MeV": 0.0,
     "detector_model": "gaussian",
     "detector_sigma_a_keV": 1.0,
     "detector_sigma_b": 0.0,
@@ -638,6 +643,7 @@ def json_to_config(data: Dict[str, Any]) -> SpectrumConfig:
         endpoint_MeV=float(data["endpoint_MeV"]),
         transition_type=str(data.get("transition_type", "A")),
         e_step_MeV=float(data.get("e_step_MeV", 0.001)),
+        neutrino_mass_MeV=float(data.get("neutrino_mass_MeV", 0.0)),
     )
 
 
@@ -683,11 +689,13 @@ def create_config_from_source(
         decay_index = kwargs.get("decay_index", None)
         e_step = kwargs.get("e_step_MeV", 0.001)
         intensity_cutoff = kwargs.get("intensity_cutoff", 0.0)
+        neutrino_mass = kwargs.get("neutrino_mass_MeV", 0.0)
         info = get_decay_info_from_paceENSDF(nuclide, decay_type, decay_index)
         return decay_info_to_config(
             info,
             e_step_MeV=e_step,
             intensity_cutoff=intensity_cutoff,
+            neutrino_mass_MeV=neutrino_mass,
         )
     elif source == "json":
         if not json_path: