Add app icon and web favicons

- Generated open-book icon on amber background (matches accent color #f59e0b)
- iOS: icon-1024.png in AppIcon.appiconset + Contents.json updated to reference it
- Web: favicon.ico (16+32), favicon-16.png, favicon-32.png, apple-touch-icon.png
  (180px), icon-192.png, icon-512.png added to ui/static/
- app.html: added full set of <link> favicon tags (ico, png, apple-touch-icon)

ios/LibNovel/LibNovel/Resources/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -1,6 +1,7 @@
 {
   "images": [
     {
+      "filename": "icon-1024.png",
       "idiom": "universal",
       "platform": "ios",
       "size": "1024x1024"