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

.llm-wiki/raw/sources/SRC-2026-05-27-004/manifest.json

@@ -0,0 +1,8 @@
+{
+  "id": "SRC-2026-05-27-004",
+  "captured": "2026-05-27",
+  "packet_version": "1.0",
+  "title": "https://cea.hal.science/cea-04796921/file/PhysRevC.110.055503.pdf",
+  "url": "https://cea.hal.science/cea-04796921/file/PhysRevC.110.055503.pdf",
+  "format": "web"
+}