[Fix] sopt-makers#94 - dimmerView animation 수정

SOPT-Stamp-iOS/Projects/Presentation/Sources/ListDetailScene/VC/ListDetailVC.swift

@@ -282,19 +282,27 @@ extension ListDetailVC {
     private func presentCompletedVC(level: StarViewLevel) {
         let missionCompletedVC = factory.makeMissionCompletedVC(starLevel: level)
         missionCompletedVC.completionHandler = {
-            UIView.animate(withDuration: 0.2, delay: 0) {
+            UIView.animate(withDuration: 0.2, delay: 0, animations: {
+                self.backgroundDimmerView.alpha = 0
+            }) { _ in
                 self.backgroundDimmerView.removeFromSuperview()
             }
         }
         self.present(missionCompletedVC, animated: true)
     }
 
     private func showDimmerView() {
+        self.backgroundDimmerView.alpha = 0
+
         self.view.addSubview(backgroundDimmerView)
 
         backgroundDimmerView.snp.makeConstraints { make in
             make.edges.greaterThanOrEqualToSuperview()
         }
+
+        UIView.animate(withDuration: 0.2, delay: 0) {
+            self.backgroundDimmerView.alpha = 1
+        }
     }
 
     // MARK: - @objc