refactor: [#115] Correct inconsistent background color code

- 배경색 입히는 코드를 두 가지 방식(ZStack / .overlay)으로 구현함.
- 코드 통일성이 부족하다고 판단하여, 한 가지 방식(ZStack)으로 통일함.

MinGenie/MinGenie/Home/HomeView.swift

@@ -27,22 +27,23 @@ struct HomeView: View {
         NavigationView {
             // 검색어 없을 때
             if searchTerm.isEmpty {
-                Color.BG.main.ignoresSafeArea()
-                    .overlay {
-                        VStack(spacing: 0) {
-                            if let tracks = selectedMusicDataModel.storedTracks {
-                                MusicItemRowView(itemRowTitle: "지난 선곡", tracks: tracks)
-                                    .padding(.bottom, 30)
-                            }
-
-                            if let tracks = musicPersonalRecommendationModel.personalRecommendationTracks {
-                                MusicItemRowView(itemRowTitle: "맞춤 랜덤 선곡", tracks: tracks)
-                            }
-
-                            Spacer()
+                ZStack {
+                    Color.BG.main.ignoresSafeArea()
+
+                    VStack(spacing: 0) {
+                        if let tracks = selectedMusicDataModel.storedTracks {
+                            MusicItemRowView(itemRowTitle: "지난 선곡", tracks: tracks)
+                                .padding(.bottom, 30)
                         }
-                        .navigationTitle("오늘의 첫곡 🎧")
+
+                        if let tracks = musicPersonalRecommendationModel.personalRecommendationTracks {
+                            MusicItemRowView(itemRowTitle: "맞춤 랜덤 선곡", tracks: tracks)
+                        }
+
+                        Spacer()
                     }
+                    .navigationTitle("오늘의 첫곡 🎧")
+                }
             } else {
                 // 검색어 있을 때
                 MusicSearchView(searchTerm: $searchTerm)