Task 540: orbital_3d + WASM + E2E Test Improvements

Status: DONE

Summary

Three-pronged test coverage improvement:

Rust orbital_3d.rs (3 new tests, 21→24)

1. Enceladus orbital radius is outside Saturn ring system (ratio ~1.7x)
2. Oblique ring crossing angle ~45° between parallel and perpendicular
3. Same-planet transfer inclination penalty gives zero ΔV

WASM wasm.test.ts (3 new tests)

1. Saturn ring crossing: ecliptic vs z-axis approach gives significantly different angles
2. Hohmann window: Earth→Jupiter within synodic period ~399 days
3. mass_compute_timeline: 3 sequential burns produce monotonically decreasing mass

E2E reports.spec.ts (2 new tests, 258→260)

1. ai-costs page has cross-reference link to tech-overview
2. Saturn ring crossing SVG diagram has text label annotations

Impact

orbital_3d.rs now tests constant relationships, geometric angles, and edge cases. WASM Saturn ring crossing, Hohmann window, and mass timeline groups all have ≥3 tests. ai-costs and side-view SVG E2E coverage expanded.