New PWA icons: slate/blue weather icon, distinct dashboard icon, safe-zone maskable

- Redrawn sun-and-cloud icon in the current palette; artwork sits inside the maskable safe zone
  (the old one was clipped by round/squircle masks and used the old warm colours)
- Separate 'any' and 'maskable' manifest entries; opaque iOS touch icons
- Station Dashboard gets its own chart icon so both installed apps are distinguishable
- Vector favicon + PNG fallback; icons verified served by both manifests

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

app/public/dashboard.html

@@ -10,7 +10,8 @@
 <meta name="apple-mobile-web-app-title" content="Station">
 <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="icon" type="image/png" sizes="192x192" href="/icons/dashboard-icon-192.png">
+<link rel="apple-touch-icon" href="/icons/dashboard-apple-touch-icon.png">
 <link rel="stylesheet" href="/pwa-safe.css">
 <title>Station Dashboard</title>
 <script src="https://cdn.jsdelivr.net/npm/chart.js@4.4.0/dist/chart.umd.min.js"></script>