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.webmanifest

@@ -8,9 +8,28 @@
   "background_color": "#070c14",
   "theme_color": "#070c14",
   "orientation": "any",
-  "categories": ["weather", "utilities"],
+  "categories": [
+    "weather",
+    "utilities"
+  ],
   "icons": [
-    { "src": "/icons/icon-192.png", "sizes": "192x192", "type": "image/png", "purpose": "any" },
-    { "src": "/icons/icon-512.png", "sizes": "512x512", "type": "image/png", "purpose": "any maskable" }
+    {
+      "src": "/icons/dashboard-icon-192.png",
+      "sizes": "192x192",
+      "type": "image/png",
+      "purpose": "any"
+    },
+    {
+      "src": "/icons/dashboard-icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "any"
+    },
+    {
+      "src": "/icons/dashboard-icon-maskable-512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "maskable"
+    }
   ]
 }