✨ Background image & appearance settings

lib/theme.dart

@@ -1,4 +1,7 @@
 import 'package:flutter/material.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+const kMaterialYouToggleStoreKey = 'app_theme_material_you';
 
 class ThemeSet {
   ThemeData light;
@@ -7,21 +10,28 @@ class ThemeSet {
   ThemeSet({required this.light, required this.dark});
 }
 
-ThemeSet createAppThemeSet() {
+Future<ThemeSet> createAppThemeSet({bool? useMaterial3}) async {
   return ThemeSet(
-    light: createAppTheme(Brightness.light),
-    dark: createAppTheme(Brightness.dark),
+    light: await createAppTheme(Brightness.light, useMaterial3: useMaterial3),
+    dark: await createAppTheme(Brightness.dark, useMaterial3: useMaterial3),
   );
 }
 
-ThemeData createAppTheme(Brightness brightness) {
+Future<ThemeData> createAppTheme(
+  Brightness brightness, {
+  bool? useMaterial3,
+}) async {
+  final prefs = await SharedPreferences.getInstance();
+
   return ThemeData(
-    useMaterial3: false,
+    useMaterial3:
+        useMaterial3 ?? (prefs.getBool(kMaterialYouToggleStoreKey) ?? false),
     colorScheme: ColorScheme.fromSeed(
       seedColor: Colors.indigo,
       brightness: brightness,
     ),
     brightness: brightness,
     iconTheme: const IconThemeData(fill: 0, weight: 400, opticalSize: 20),
+    scaffoldBackgroundColor: Colors.transparent,
   );
 }