Ryan Malloy 46c8a30575 Add v0.16.0: twilight dawn/dusk, lunar phase, planet apparent magnitude
Twilight: 6 functions (civil/nautical/astronomical × dawn/dusk) reusing
the existing find_next_crossing() bisection search with Sun depression
angle thresholds (-6°, -12°, -18°). Returns NULL for polar regions
where the threshold is never reached.

Lunar phase: 4 functions computing Sun-Earth-Moon geometry from VSOP87
+ ELP2000-82B. Phase angle [0,360) via elongation + cross product
z-component for waxing/waning discrimination. 8 named phases in 45°
bins. Moon age approximated from phase angle and mean synodic month.

Planet magnitude: Mallama & Hilton (2018) polynomial model with VSOP87
heliocentric distances and phase angle via law of cosines. All 7
planets (Mercury-Neptune, excluding Earth). Saturn ring tilt not
modeled.

151 → 162 SQL objects. 26 → 27 test suites, all passing.
2026-02-26 12:42:01 -07:00
..
2026-02-17 13:36:22 -07:00