Add functional login page

lib/storage_helper.dart

@@ -0,0 +1,22 @@
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+
+enum StorageKey { url, jwt, email, password }
+
+class StorageHelper {
+  late FlutterSecureStorage secureStorage;
+
+  StorageHelper() {
+    AndroidOptions getAndroidOptions() => const AndroidOptions(
+          encryptedSharedPreferences: true,
+        );
+    secureStorage = FlutterSecureStorage(aOptions: getAndroidOptions());
+  }
+
+  Future<String?> read(StorageKey key) {
+    return secureStorage.read(key: key.name);
+  }
+
+  Future<void> write(StorageKey key, String value) {
+    return secureStorage.write(key: key.name, value: value);
+  }
+}