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/wiki/sources/SRC-2026-05-27-002.md

@@ -0,0 +1,40 @@
+---
+type: source
+format: markdown
+source_id: SRC-2026-05-27-002
+raw_path: raw/sources/SRC-2026-05-27-002/extracted.md
+captured: 2026-05-27
+status: skeleton
+---
+
+# 01-shape-factors.md
+
+## Summary
+
+[LLM: Replace with 2-3 paragraph summary of key content]
+
+> _Auto-preview: --- title: "10 – Nuclear Structure Effects" date: 2026-04-26 tags: - beta-spectrum/nuclear-structure status: active aliases: [Shape Factor, C(Z,W), Form Factors] cssclasses: [] relatedcomponents: [[corrections/06-recoil]], --- Nuclear Structure Effects — The Shape Factor $C(Z,W)$ Overview Nuclear structure effects are encapsulated in the shape factor $C(Z,W)$ which multiplies the phase space × Fermi function. This is distinct from electrostatic finite size corrections ([[corrections/02-finite-si..._
+
+## Key Takeaways
+
+- [LLM: Most important point]
+- [LLM: Second important point]
+- [LLM: Third important point]
+
+## Entities Mentioned
+
+- [[entity-name]]
+
+## Concepts Mentioned
+
+- [[concept-name]]
+
+## Notable Quotes
+
+> [LLM: Important quote] — attribution
+
+## Source Packet
+
+- **ID:** `[[sources/SRC-2026-05-27-002]]`
+- **Extracted:** [raw/sources/SRC-2026-05-27-002/extracted.md](../raw/sources/SRC-2026-05-27-002/extracted.md)
+- **Manifest:** [raw/sources/SRC-2026-05-27-002/manifest.json](../raw/sources/SRC-2026-05-27-002/manifest.json)