M1: object cards, time scrubber, night mode !3

Stacked on !2 (targets m1-sky-shell).

• SkyEngine: rise/set and next lunar quarter. Sun, Saturn and Moon rise/set match JPL Horizons within 2 minutes.
• SkyRenderer: tap hit testing, constellation names, night style.
• App: tap a planet or the Moon for a card; tap near a constellation for its name; time scrubber (±12 h, Now); night mode toggle. All engine calls go through one actor (Astronomy Engine is not thread-safe).

Verified in the iOS 27 simulator: Moon card, night mode, scrubbing to 01:21 shows Saturn and Uranus. swift test: 11 pass.