Install-as-app guide and iPhone safe-area support

- Install banner (phones), Settings guide and dialog with iPhone/iPad and Android steps,
  native Install button where supported; steps also on the dashboard Account page
- apple-touch-icon now a PNG (iOS ignores SVG icons)
- Shared pwa-safe.css: dark cap behind the status bar/Dynamic Island in the installed app,
  inset-aware offline banner, pull-to-refresh, bottom bars, full-screen map, dialogs
- Landscape-aware content gutters; measured top-bar height; viewport-fit=cover on every page

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

app/public/dashboard-login.html

@@ -9,6 +9,7 @@
 <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
 <link rel="manifest" href="/dashboard.webmanifest">
 <link rel="apple-touch-icon" href="/icons/apple-touch-icon.png">
+<link rel="stylesheet" href="/pwa-safe.css">
 <title>Station Dashboard — Sign In</title>
 <style>
 *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }