Poll GET /api/stats ~30s for rail integers (404 falls back to overlay
array lengths). Keyboard: ? cheat sheet, L layers, R reset, Esc closes
panels; F/S left unbound. Cheap sun-position day/night overlay default
off. Camera/HLS thumbs only at zoom >= 12. NOAA SWPC Kp chip in the
status strip (browser-direct; hide on failure).
