Fix tvOS focus trap on empty Home after fresh install

Render a focusable empty state on tvOS Home when no sections have content,
with an "Open Sources" button that switches the sidebar selection. Without
a focusable view the tvOS focus engine had no target, leaving the sidebar
unreachable after the initial iCloud alert was dismissed.

Also wire the selectedSidebarItem onChange handler into the tvOS TabView,
which was missing and prevented programmatic sidebar selection.

Yattee/Views/Home/HomeView.swift

@@ -166,12 +166,63 @@ struct HomeView: View {
 
     // MARK: - Main Content
 
+    #if os(tvOS)
+    /// True on tvOS when no Home section would render content — prevents a focus trap
+    /// on fresh installs where the detail pane would otherwise be completely empty.
+    private var isHomeEmpty: Bool {
+        let sections = settingsManager?.visibleSections() ?? HomeSectionItem.defaultOrder.filter { HomeSectionItem.defaultVisibility[$0] == true }
+        for section in sections {
+            switch section {
+            case .continueWatching:
+                if !recentContinueWatching.isEmpty { return false }
+            case .feed:
+                if !feedCache.videos.isEmpty { return false }
+            case .bookmarks:
+                if !recentBookmarks.isEmpty { return false }
+            case .history:
+                if !recentHistory.isEmpty { return false }
+            case .downloads:
+                break
+            case .instanceContent, .mediaSource:
+                return false
+            }
+        }
+        return true
+    }
+
+    private var emptyHomeView: some View {
+        VStack(spacing: 32) {
+            VStack(spacing: 12) {
+                Text(String(localized: "home.tvos.empty.title"))
+                    .font(.title2)
+                    .fontWeight(.semibold)
+                Text(String(localized: "home.tvos.empty.message"))
+                    .foregroundStyle(.secondary)
+                    .multilineTextAlignment(.center)
+            }
+            Button {
+                appEnvironment?.navigationCoordinator.selectedSidebarItem = .sources
+            } label: {
+                Label(String(localized: "home.tvos.empty.openSources"), systemImage: "externaldrive.connected.to.line.below")
+                    .padding(.horizontal, 16)
+                    .padding(.vertical, 8)
+            }
+        }
+        .padding(60)
+        .frame(maxWidth: .infinity, maxHeight: .infinity)
+    }
+    #endif
+
     @ViewBuilder
     private var mainContent: some View {
         #if os(tvOS)
-        ScrollView {
-            LazyVStack(spacing: 0) {
-                homeContent
+        if isHomeEmpty {
+            emptyHomeView
+        } else {
+            ScrollView {
+                LazyVStack(spacing: 0) {
+                    homeContent
+                }
             }
         }
         #else