refactor: refine CLI options and enhance debug logging

- Remove --mode, --transition-type, and --decay-index CLI flags
  (parameters now come from ENSDF data or custom JSON input)
- Clarify energy units in all CLI help text (MeV throughout, keV for detector params)
- Enhance logging verbosity:
  - -v (INFO): shows source, component initialization, workflow steps
  - -vv (DEBUG): shows detailed internals of all spectrum components
    (parameters, evaluation counts, input/output ranges)
- Improve CSV headers with element notation (e.g. Tc99 -> Ru99)
- Add CONVENTIONS.md documenting energy unit and logging conventions
- Update TODO.md with completion status

beta_spectrum/components/phase_space.py

@@ -15,6 +15,7 @@ class PhaseSpace(SpectrumComponent):
         transition_type: str = "A",
         m_e: float = 1.0,
         m_nu: float = 0.0,
+        logger=None,
     ):
         """
         Create instance of phase space with given decay parameters.
@@ -25,7 +26,9 @@ class PhaseSpace(SpectrumComponent):
             transition_type: allowed or N-order forbidden, should be [A, F1, F1U, F2, F2U, F3, F3U, F4]
             m_e: 1st body mass (electron by default: m_e = 1)
             m_nu:2nd body mass (massless neutrino by default: m_nu = 0)
+            logger: Optional logger for debug/info output
         """
+        super().__init__(logger=logger)
         self.tr_type = transition_type
         if self.tr_type not in ["A", "F1", "F1U", "F2", "F2U", "F3", "F3U", "F4"]:
             raise ValueError(