Match the browser/OS chrome to the theme and clear the status bar

The app now sets theme-color, color-scheme and the page background from the chosen theme,
so the iPad status-bar area no longer shows a light band over a dark theme. Every top bar
leaves room for the status bar via a safe-top class (replacing a rule that padded every
<header>). Install defaults match the paper theme.

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

public/manifest.json

@@ -6,8 +6,8 @@
   "scope": "/",
   "display": "standalone",
   "orientation": "any",
-  "background_color": "#f8fafc",
-  "theme_color": "#0f172a",
+  "background_color": "#faf7f0",
+  "theme_color": "#f1ece0",
   "icons": [
     {
       "src": "/icon-192.png",