Hide the home navigation bar if the user is not a member of any Space.

https://github.com/element-hq/element-meta/issues/2906: `The tab bar with the option to view joined spaces is only shown when the user has at least one space that they have joined (because otherwise they have no clue what to do in here).`

features/home/impl/src/main/kotlin/io/element/android/features/home/impl/HomePresenter.kt

@@ -74,6 +74,12 @@ class HomePresenter(
             }
         }
 
+        LaunchedEffect(homeSpacesState.spaceRooms.isEmpty()) {
+            // If the last space is left, ensure that the Chat view is rendered.
+            if (homeSpacesState.spaceRooms.isEmpty()) {
+                currentHomeNavigationBarItemOrdinal = HomeNavigationBarItem.Chats.ordinal
+            }
+        }
         val snackbarMessage by snackbarDispatcher.collectSnackbarMessageAsState()
         return HomeState(
             matrixUser = matrixUser.value,

features/home/impl/src/main/kotlin/io/element/android/features/home/impl/HomeState.kt

@@ -29,4 +29,5 @@ data class HomeState(
     val eventSink: (HomeEvents) -> Unit,
 ) {
     val displayActions = currentHomeNavigationBarItem == HomeNavigationBarItem.Chats
+    val showNavigationBar = isSpaceFeatureEnabled && homeSpacesState.spaceRooms.isNotEmpty()
 }

features/home/impl/src/main/kotlin/io/element/android/features/home/impl/HomeStateProvider.kt

@@ -36,6 +36,8 @@ open class HomeStateProvider : PreviewParameterProvider<HomeState> {
                         summaries = generateRoomListRoomSummaryList(),
                     )
                 ),
+                // For the bottom nav bar to be visible in the preview, the user must be member of at least one space
+                homeSpacesState = aHomeSpacesState(),
             ),
             aHomeState(
                 isSpaceFeatureEnabled = true,

features/home/impl/src/main/kotlin/io/element/android/features/home/impl/HomeView.kt

@@ -194,7 +194,7 @@ private fun HomeScaffold(
             )
         },
         bottomBar = {
-            if (state.isSpaceFeatureEnabled) {
+            if (state.showNavigationBar) {
                 NavigationBar(
                     containerColor = Color.Transparent,
                     modifier = Modifier