Add initial project structure and configuration files for iOS and Android

lib/security/secure_storage.dart

@@ -0,0 +1,34 @@
+import 'dart:convert';
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+
+class SecureStorage {
+  final FlutterSecureStorage _storage;
+  
+  SecureStorage(): _storage = const FlutterSecureStorage();
+  
+  Future<void> write(String key, dynamic value) async {
+    final stringValue = value is String 
+        ? value 
+        : json.encode(value);
+    await _storage.write(key: key, value: stringValue);
+  }
+  
+  Future<dynamic> read(String key) async {
+    final value = await _storage.read(key: key);
+    if (value == null) return null;
+    
+    try {
+      return json.decode(value);
+    } catch (_) {
+      return value;
+    }
+  }
+  
+  Future<void> delete(String key) async {
+    await _storage.delete(key: key);
+  }
+  
+  Future<void> deleteAll() async {
+    await _storage.deleteAll();
+  }
+}