Add Contribution view with review and donation buttons

Toki Trainer/Views/ContentView.swift

@@ -6,6 +6,7 @@
 //
 
 import SwiftUI
+import StoreKit
 import CoreData
 
 extension String: Identifiable {
@@ -14,7 +15,9 @@ extension String: Identifiable {
 
 struct ContentView: View {
     @Environment(\.managedObjectContext) private var viewContext
-    
+
+    @StateObject var transactions: TransactionObserver = TransactionObserver()
+
     var body: some View {
         TabView {
             DictionaryView()
@@ -32,9 +35,15 @@ struct ContentView: View {
                     Image(systemName: "character.textbox")
                     Text("Flash Cards")
                 }
+            ContributeView()
+                .tabItem {
+                    Image(systemName: "heart.circle.fill")
+                    Text("Contribute")
+                }
         }
+        .environmentObject(transactions)
     }
-    
+
     func openPartsOfSpeechView() {
         print("Button pressed.")
     }