feat: enhance CompactNavigation with CMS submenu and toggle functionality

android-app/app/src/main/java/de/harheimertc/ui/components/AppNavigationHeader.kt

@@ -72,6 +72,11 @@ private fun CompactNavigation(
     onNavigate: (String) -> Unit,
     navigationState: NavigationUiState = NavigationUiState(),
 ) {
+    val section = menuSection(selectedRoute)
+    val subItems = submenu(section, navigationState)
+    var cmsExpanded = androidx.compose.runtime.remember { androidx.compose.runtime.mutableStateOf(false) }
+    val navigateAndClose: (String) -> Unit = { route -> cmsExpanded.value = false; onNavigate(route) }
+
     BrandRow(onLogin = { onNavigate(Destinations.Login.route) })
     Row(
         modifier = Modifier.horizontalScroll(rememberScrollState()),
@@ -83,6 +88,7 @@ private fun CompactNavigation(
         CompactLink("Training", Destinations.Training.route, selectedRoute, onNavigate)
         CompactLink("Termine", Destinations.Termine.route, selectedRoute, onNavigate)
         CompactLink("Spielplan", Destinations.Spielplan.route, selectedRoute, onNavigate)
+        CompactLink("Newsletter", Destinations.NewsletterSubscribe.route, selectedRoute, onNavigate)
         if (navigationState.showGallery) {
             CompactLink("Galerie", Destinations.Gallery.route, selectedRoute, onNavigate)
         }
@@ -94,6 +100,46 @@ private fun CompactNavigation(
             CompactLink("CMS", Destinations.Cms.route, selectedRoute, onNavigate)
         }
     }
+
+    val cmsIndex = subItems.indexOfFirst { it.label == "CMS" }
+    val cmsChildren = if (cmsIndex >= 0) subItems.subList(cmsIndex + 1, subItems.size) else emptyList<MenuTarget>()
+    if (cmsChildren.any { it.route == selectedRoute }) {
+        cmsExpanded.value = true
+    }
+
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .horizontalScroll(rememberScrollState())
+            .padding(top = 3.dp),
+        horizontalArrangement = Arrangement.spacedBy(4.dp),
+    ) {
+        subItems.forEachIndexed { idx, item ->
+            if (idx == cmsIndex) {
+                SubLink(item.label, item.route == selectedRoute) {
+                    cmsExpanded.value = !cmsExpanded.value
+                }
+            } else if (idx > cmsIndex && cmsIndex >= 0) {
+                // CMS children are rendered below when expanded.
+            } else {
+                SubLink(item.label, item.route == selectedRoute) { navigateAndClose(item.route) }
+            }
+        }
+    }
+
+    if (cmsExpanded.value && cmsChildren.isNotEmpty()) {
+        Row(
+            modifier = Modifier
+                .fillMaxWidth()
+                .horizontalScroll(rememberScrollState())
+                .padding(top = 6.dp, bottom = 3.dp),
+            horizontalArrangement = Arrangement.spacedBy(8.dp),
+        ) {
+            cmsChildren.forEach { child ->
+                SubLink(child.label, child.route == selectedRoute) { onNavigate(child.route) }
+            }
+        }
+    }
 }
 
 @Composable