feat: Add welcome wizard for new users

- Implemented a multi-page welcome wizard to introduce new users to the app's features.
- Added localization support for the wizard in English, Spanish, French, Croatian, Italian, and Slovenian.
- Integrated wizard completion state management using SharedPreferences.
- Updated main app flow to show the wizard if it hasn't been completed.
- Added a settings option to view the welcome tutorial again.

lib/services/wizard_preferences.dart

@@ -0,0 +1,42 @@
+import 'package:shared_preferences/shared_preferences.dart';
+
+/// Service to manage welcome wizard preferences and state
+class WizardPreferences {
+  static const String _wizardCompletedKey = 'wizard_completed';
+  static const String _wizardVersionKey = 'wizard_version';
+  static const int _currentWizardVersion = 1;
+
+  /// Check if the welcome wizard has been completed
+  static Future<bool> isWizardCompleted() async {
+    final prefs = await SharedPreferences.getInstance();
+    final completed = prefs.getBool(_wizardCompletedKey) ?? false;
+    final version = prefs.getInt(_wizardVersionKey) ?? 0;
+
+    // Re-show wizard if version has changed (for major updates)
+    return completed && version >= _currentWizardVersion;
+  }
+
+  /// Mark the welcome wizard as completed
+  static Future<void> setWizardCompleted(bool completed) async {
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setBool(_wizardCompletedKey, completed);
+
+    if (completed) {
+      // Store current version when wizard is completed
+      await prefs.setInt(_wizardVersionKey, _currentWizardVersion);
+    }
+  }
+
+  /// Get the wizard version last shown to the user
+  static Future<int> getWizardVersion() async {
+    final prefs = await SharedPreferences.getInstance();
+    return prefs.getInt(_wizardVersionKey) ?? 0;
+  }
+
+  /// Reset wizard state (useful for testing or re-showing tutorial)
+  static Future<void> resetWizard() async {
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setBool(_wizardCompletedKey, false);
+    await prefs.setInt(_wizardVersionKey, 0);
+  }
+}