refactoring

lib/core/theme/theme_provider.dart

@@ -0,0 +1,42 @@
+import 'package:flutter/material.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+/// Provider de thème — light / dark avec persistance
+class ThemeProvider extends ChangeNotifier {
+  static const String _key = 'uf_theme_mode';
+
+  ThemeMode _mode;
+
+  ThemeProvider({ThemeMode initial = ThemeMode.system}) : _mode = initial;
+
+  ThemeMode get mode => _mode;
+
+  bool get isDark => _mode == ThemeMode.dark;
+
+  Future<void> toggle() async {
+    _mode = isDark ? ThemeMode.light : ThemeMode.dark;
+    notifyListeners();
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setString(_key, _mode.name);
+  }
+
+  Future<void> setMode(ThemeMode mode) async {
+    if (_mode == mode) return;
+    _mode = mode;
+    notifyListeners();
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setString(_key, mode.name);
+  }
+
+  /// Charge le thème persisté depuis les préférences
+  static Future<ThemeProvider> load() async {
+    final prefs = await SharedPreferences.getInstance();
+    final stored = prefs.getString(_key);
+    final mode = switch (stored) {
+      'light' => ThemeMode.light,
+      'dark'  => ThemeMode.dark,
+      _       => ThemeMode.system,
+    };
+    return ThemeProvider(initial: mode);
+  }
+}