Add features:

- manifest.json with PNG icon set.
 - reset option against QuickLinks storage
 - 'Preferences' store, ready for preferences page - including location boolean... Important!
 - Minor service-worker improvements for better offline fallbacks

static/manifest.json

@@ -0,0 +1,62 @@
+{
+    "name": "OwlBoard",
+    "short_name": "OwlBoard",
+    "description": "Real-time UK rail data and operational tools for staff and enthusiasts.",
+    "id": "/",
+    "start_url": "/",
+    "scope": "/",
+    "display": "standalone",
+    "display_override": [
+        "window-controls-overlay",
+        "standalone",
+        "minimal-ui"
+    ],
+    "background_color": "#404c55",
+    "theme_color": "#4fd1d1",
+    "orientation": "portrait",
+    "categories": [
+        "transportation",
+        "utilities"
+    ],
+    "dir": "ltr",
+    "lang": "en-GB",
+    "prefer_related_applications": false,
+    "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"
+        },
+        {
+            "src": "/icons/maskable-512.png",
+            "sizes": "512x512",
+            "type": "image/png",
+            "purpose": "maskable"
+        }
+    ],
+    "shortcuts": [
+        {
+            "name": "Find PIS",
+            "short_name": "PIS",
+            "description": "Find PIS Codes fast",
+            "url": "/pis",
+            "icons": [
+                {
+                    "src": "/icons/icon-192.png",
+                    "sizes": "192x192"
+                }
+            ]
+        }
+    ],
+    "handle_links": "preferred",
+    "launch_handler": {
+        "client_mode": "focus-existing"
+    }
+}