added categories, import export, settings

lib/main.dart

@@ -3,7 +3,8 @@ library;
 
 import 'package:flutter/material.dart';
 
-import 'scan_screen.dart';
+import 'home_shell.dart';
+import 'services/app_settings.dart';
 import 'services/product_repository.dart';
 import 'utils/app_theme.dart';
 import 'utils/constants.dart';
@@ -13,20 +14,48 @@ void main() {
   runApp(ReceipityApp());
 }
 
-class ReceipityApp extends StatelessWidget {
+class ReceipityApp extends StatefulWidget {
   ReceipityApp({super.key, ProductRepository? repository})
       : repository = repository ?? ProductRepository();
 
   final ProductRepository repository;
 
+  @override
+  State<ReceipityApp> createState() => _ReceipityAppState();
+}
+
+class _ReceipityAppState extends State<ReceipityApp> {
+  late final AppSettings _settings;
+
+  @override
+  void initState() {
+    super.initState();
+    _settings = AppSettings(widget.repository);
+    _settings.addListener(_onSettings);
+    _settings.load();
+  }
+
+  @override
+  void dispose() {
+    _settings.removeListener(_onSettings);
+    _settings.dispose();
+    super.dispose();
+  }
+
+  void _onSettings() => setState(() {});
+
   @override
   Widget build(BuildContext context) {
-    return MaterialApp(
-      title: kAppName,
-      debugShowCheckedModeBanner: false,
-      theme: AppTheme.light(),
-      darkTheme: AppTheme.dark(),
-      home: ScanScreen(repository: repository),
+    return SettingsScope(
+      settings: _settings,
+      child: MaterialApp(
+        title: kAppName,
+        debugShowCheckedModeBanner: false,
+        theme: AppTheme.light(),
+        darkTheme: AppTheme.dark(),
+        themeMode: _settings.darkMode ? ThemeMode.dark : ThemeMode.light,
+        home: HomeShell(repository: widget.repository),
+      ),
     );
   }
 }