docs: add algorithm entries for ProlepticDate, BiblicalCalendarHelper, CelestialEventDetector; add implementation complete banner
docs: add Algorithm Reference page and update Home Add comprehensive Algorithm-Reference.md covering all algorithm families: timekeeping, solar, lunar, topocentric parallax, planetary, coordinate transforms, nutation/precession, phenomena (rise/set, eclipses, seasons, planetary events), fixed stars, and SPICE/BSP import. Update Home.md to link to Algorithm Reference at the top of documentation. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>