Fix macOS 12 not visible on first start

.gitignore

@@ -1,3 +1,4 @@
 DerivedData/
+.DerivedData/
 .DS_Store
 xcuserdata/

QuickDrop/AppDelegate.swift

@@ -238,6 +238,7 @@ class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCenterDele
             if let welcomeWindow, !Settings.sharedInstance.appLaunchedBefore {
                 runAfter(seconds: 0.2) {
                     IntroductionSheetManager.sharedInstance.openIntroductionWindow(on: welcomeWindow, startReceiving: self.startReceiving) {
+                        self.startReceiving()
                         Settings.sharedInstance.appLaunchedBefore = true
                     }
                 }

QuickDrop/View/UserManual/WelcomeScreen.swift

@@ -70,7 +70,6 @@ struct WelcomeScreen: View {
             .listStyle(SidebarListStyle())
             
             Divider()
-                .opacity(colorScheme == .light ? 1 : 0.5)
                 .edgesIgnoringSafeArea(.vertical)
             
             ZStack {