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/index.html

@@ -15,10 +15,23 @@
     <meta name="theme-color" content="#0d2f3c" />
     <meta name="description" content="Musik und Hörbücher für die MusicMouse" />
 
-    <!-- iOS does not read the manifest for home-screen installs; these are what it uses. -->
+    <!-- iOS takes start_url from the manifest, but the title, icon and status bar from
+         these tags. -->
     <meta name="apple-mobile-web-app-capable" content="yes" />
     <meta name="mobile-web-app-capable" content="yes" />
     <meta name="apple-mobile-web-app-title" content="Musik" />
+    <!-- A home-screen install starts at the manifest's start_url, not at the address it
+         was added from, so `?parentMode=1` would be lost. Opened with it, the page offers
+         a second manifest whose start_url keeps it - "Add to Home Screen" from a parent's
+         URL installs the parents' app, under its own name. Inline, so the tags are
+         switched before anything reads them. -->
+    <script>
+      if (new URLSearchParams(location.search).get("parentMode") === "1") {
+        document.querySelector('link[rel="manifest"]').href = "/manifest-parents.webmanifest";
+        document.querySelector('meta[name="apple-mobile-web-app-title"]').content = "Musik Eltern";
+        document.title = "Musik Delfin Eltern";
+      }
+    </script>
     <!-- An opaque status bar, so the page starts below it - not black-translucent. That
          one ran the page under the clock, which put every top-anchored control behind
          it unless each remembered its inset, and since iOS 26 it also sizes the app one