From Claude Artifact to Production PWA: Building VitaminD Explorer

It started with a simple question: can I synthesize vitamin D today in London? I'd been reading about how latitude, season, and skin type determine whether sunlight can actually trigger vitamin D production. The science is clear — below a certain solar elevation angle (~45–50°), UVB radiation is too weak for synthesis regardless of how long you stay outside. But figuring out when that window opens for a given city on a given day? That's a calculation involving solar declination , hour angles, an