feat: window title hides/shows with toolbar on idle timeout

Sources/MiniPlayerApp.swift

@@ -266,6 +266,8 @@ struct PlayerContentView: View {
             }
         }
         .onChange(of: showToolbar) { _, newValue in
+            // 同步控制窗口标题的显示/隐藏
+            NSApplication.shared.windows.first?.titleVisibility = newValue ? .visible : .hidden
             if newValue {
                 resetHideTimer()
             } else {
@@ -275,6 +277,10 @@ struct PlayerContentView: View {
         .onDisappear {
             hideTimer?.invalidate()
         }
+        .onAppear {
+            // 初始状态：标题随toolbar一起隐藏
+            NSApplication.shared.windows.first?.titleVisibility = .hidden
+        }
     }
 }