Add PWA support for iOS home screen install

- Web app manifest (standalone display, NOMAD branding, icons)
- Service worker with Workbox caching (map tiles, API, uploads, CDN)
- SVG app icon + PNG generation script via sharp
- Apple meta tags (web-app-capable, black-translucent status bar)
- Dynamic theme-color for dark/light mode
- Safe area insets for notch devices

client/src/index.css

@@ -3,7 +3,17 @@
 @tailwind utilities;
 
 html { height: 100%; overflow: hidden; }
-body { height: 100%; overflow: auto; overscroll-behavior: none; -webkit-overflow-scrolling: touch; }
+body {
+  height: 100%;
+  overflow: auto;
+  overscroll-behavior: none;
+  -webkit-overflow-scrolling: touch;
+  /* PWA safe areas (notch, home indicator) */
+  padding-top: env(safe-area-inset-top);
+  padding-bottom: env(safe-area-inset-bottom);
+  padding-left: env(safe-area-inset-left);
+  padding-right: env(safe-area-inset-right);
+}
 
 .atlas-tooltip {
   background: rgba(10, 10, 20, 0.6) !important;