Task 599: ADR Quality Audit + Orekit Cross-Validation

Status: DONE

All 15 ADRs (001-015) already have "Alternatives Considered" and "Assumptions" sections
Added 31 regression tests in report-data-validation.test.ts to prevent future ADRs from missing these sections
ADR template (000-template.md) also includes both sections

CLAUDE.md explicitly requested cross-validation against trusted simulators like Orekit
Installed orekit-jpype (Java-bridged Orekit) with DE-440 ephemeris data
Created cross_validation/validate_orekit.py with 62 checks across 10 categories:

1. Gravitational parameters (GM) — 7 bodies validated against Orekit's JPL DE440 values

2. Circular orbit velocities — LEO, GEO, Earth orbit

3. Hohmann transfer ΔV — 5 transfers (LEO→GEO, Earth→Mars/Jupiter/Saturn/Uranus)

4. Orbital periods — 5 planets + LEO

5. Sphere of Influence radii — Jupiter, Earth, Saturn, Uranus

6. Flyby mechanics — turn angle, v_periapsis, powered v∞ amplification

7. Kepler equation — 6 test cases (E and ν, machine-precision match)

8. Orbital elements → state vector — eccentric inclined + Halley-like orbits

9. Numerical propagation — energy conservation to 1e-14

10. Fundamental constants — g0

Sun GM: Rust vs Orekit match to 2e-12 relative error
Jupiter/Saturn GM: ~2e-4 difference (DE430 vs DE440 ephemeris versions) — documented
Kepler equation: machine-precision agreement (1e-16)
Hohmann ΔV: ~1e-12 relative error
State vectors: position exact, velocity ~8e-9 (from GM difference propagation)