新功能：添加了快捷键和对应的tooltip

ChuanhuWallpaper/Components/SaveButton.swift

@@ -25,6 +25,7 @@ struct SaveButton: View {
             Alert(title: Text("An Error Occured"), message: Text(errorMessage), dismissButton: .cancel())
         }
         .keyboardShortcut("s")
+        .help("⌘ S")
     }
 
     private func save() {

ChuanhuWallpaper/ContentView.swift

@@ -50,6 +50,7 @@ struct ContentView: View {
                         }
                     }
                         .keyboardShortcut(KeyEquivalent.escape, modifiers: [])
+                        .help("Esc")
                         .offset(x: wallpapers.isEmpty ? 200 : 0)
                         .animation(.spring(), value: wallpapers)
                     , alignment: .trailing

ChuanhuWallpaper/View/WallpaperPlaceholderCell.swift

@@ -64,6 +64,7 @@ struct WallpaperPlaceholderCell: View {
             Text("Choose Photo(s)...").fixedSize(horizontal: false, vertical: true)
         }
         .keyboardShortcut("i")
+        .help("⌘ I")
     }
 }