savedPreferences for themes

frontend_splatournament_manager/lib/providers/theme_provider.dart

@@ -1,12 +1,51 @@
 import 'package:flutter/material.dart';
+import 'package:shared_preferences/shared_preferences.dart';
 
 class ThemeProvider extends ChangeNotifier {
+  static const String _themeKey = 'theme_mode';
   ThemeMode _themeMode = ThemeMode.system;
 
   ThemeMode get theme => _themeMode;
 
-  void setTheme(ThemeMode mode) {
-    _themeMode = mode;
+  ThemeProvider() {
+    _loadTheme();
+  }
+
+  Future<void> _loadTheme() async {
+    final prefs = await SharedPreferences.getInstance();
+    final themeName = prefs.getString(_themeKey) ?? 'system';
+    _themeMode = _themeFromString(themeName);
     notifyListeners();
   }
+
+  Future<void> setTheme(ThemeMode mode) async {
+    _themeMode = mode;
+    notifyListeners();
+    
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setString(_themeKey, _themeToString(mode));
+  }
+
+  String _themeToString(ThemeMode mode) {
+    switch (mode) {
+      case ThemeMode.light:
+        return 'light';
+      case ThemeMode.dark:
+        return 'dark';
+      case ThemeMode.system:
+        return 'system';
+    }
+  }
+
+  ThemeMode _themeFromString(String theme) {
+    switch (theme) {
+      case 'light':
+        return ThemeMode.light;
+      case 'dark':
+        return ThemeMode.dark;
+      case 'system':
+      default:
+        return ThemeMode.system;
+    }
+  }
 }