Pick random letter and category at startup

android/gradle.properties

 org.gradle.jvmargs=-Xmx1536M
 android.useAndroidX=true
 android.enableJetifier=true
-app.versionName=1.1.1
-app.versionCode=4
+app.versionName=1.1.2
+app.versionCode=5

lib/main.dart

@@ -137,6 +137,12 @@ class _MyHomePageState extends State<MyHomePage> {
     });
   }
 
+  @override
+  void initState() {
+    _pickRandomLetter();
+    _pickRandomCategory();
+  }
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(