PWA: a home-screen install from ?parentMode=1 keeps parent mode

iOS starts an installed web app at the manifest's start_url ("/"), so the
query parameter was dropped. Opened with ?parentMode=1, the page now points at
a second manifest whose start_url keeps it, and names the app "Musik Eltern".

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

web/public/manifest-parents.webmanifest

@@ -0,0 +1,33 @@
+{
+  "name": "Musik Delfin Eltern",
+  "short_name": "Musik Eltern",
+  "description": "Musik und Hörbücher für die MusicMouse",
+  "start_url": "/?parentMode=1",
+  "scope": "/",
+  "display": "standalone",
+  "orientation": "any",
+  "background_color": "#0d2f3c",
+  "theme_color": "#0d2f3c",
+  "lang": "de",
+  "icons": [
+    {
+      "src": "/icon-192.png",
+      "sizes": "192x192",
+      "type": "image/png",
+      "purpose": "any"
+    },
+    {
+      "src": "/icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "any"
+    },
+    {
+      "src": "/icon-maskable-512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "maskable"
+    }
+  ],
+  "id": "/?parentMode=1"
+}