Add forward skip to mini player, home-screen app support, cover fallback

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

manifest.webmanifest

@@ -0,0 +1,15 @@
+{
+  "name": "Audiobooks",
+  "short_name": "Audiobooks",
+  "description": "Listen to your OpenAudible library",
+  "start_url": "/",
+  "scope": "/",
+  "display": "standalone",
+  "orientation": "portrait",
+  "background_color": "#0f0f12",
+  "theme_color": "#0f0f12",
+  "icons": [
+    {"src": "/icon-192.png", "sizes": "192x192", "type": "image/png"},
+    {"src": "/icon-512.png", "sizes": "512x512", "type": "image/png"}
+  ]
+}