Initial commit: Eventify frontend

lib/core/theme_manager.dart

@@ -0,0 +1,32 @@
+// lib/core/theme_manager.dart
+import 'package:flutter/material.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+class ThemeManager {
+  ThemeManager._();
+
+  static const String _prefKey = 'is_dark_mode';
+  static final ValueNotifier<ThemeMode> themeMode = ValueNotifier(ThemeMode.light);
+
+  /// Call during app startup to load saved preference.
+  static Future<void> init() async {
+    final prefs = await SharedPreferences.getInstance();
+    final isDark = prefs.getBool(_prefKey) ?? false;
+    themeMode.value = isDark ? ThemeMode.dark : ThemeMode.light;
+  }
+
+  /// Set theme and persist
+  static Future<void> setThemeMode(ThemeMode mode) async {
+    themeMode.value = mode;
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setBool(_prefKey, mode == ThemeMode.dark);
+  }
+
+  static bool get isDark => themeMode.value == ThemeMode.dark;
+
+  /// Toggle helper
+  static Future<void> toggle() async {
+    final newMode = themeMode.value == ThemeMode.dark ? ThemeMode.light : ThemeMode.dark;
+    await setThemeMode(newMode);
+  }
+}