M4: System tab (orrery and probes) !11

Stacked on !10 (targets m3-launches).

• SkyEngine: heliocentricEcliptic, heliocentricEarth; all C calls behind one NSRecursiveLock (the System tab draws on the main thread while the Sky tab builds scenes in the background).
• SkyRenderer: Spacecraft (bundled Horizons vectors, 132 KB), OrreryScale (linear to 1 AU, log to 230 AU), OrreryView.
• App: System tab: orrery, time slider 1958–2050 with play, distances and one-way light time.

Note: after adding a package resource, a clean build was needed for it to reach the app bundle.

Verified in the iOS 27 simulator (Voyager 1 172.1 AU on 2026-10-17). Device build compiles. swift test: 26 pass.