Fix mouse-wheel scrolling in the main app and the dashboard sun arc

- overscroll-behavior moved from <body> to <html>: with html+body both overflow-x:hidden,
  body is a scroll container and the rule blocked wheel scrolling from reaching the page
- sunTimes returned the neighbouring day's sunrise/sunset (julian-day rounding), so midday
  looked like night; align results to the requested local day

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

app/public/app-ui.css

@@ -5,7 +5,8 @@
   --topbar-h: 58px;
 }
 html { -webkit-text-size-adjust: 100%; -webkit-tap-highlight-color: transparent; }
-body { overscroll-behavior-y: none; }
+/* on <html> (the viewport): putting this on <body> can block wheel scrolling when body is a scroll container */
+html { overscroll-behavior-y: none; }
 button, a, summary { touch-action: manipulation; }
 
 /* ── Layout ── */