feat: Implement switching between accounts (multi user support), still WIP

lib/features/login/model/user_account.dart

@@ -0,0 +1,20 @@
+import 'package:hive_flutter/adapters.dart';
+import 'package:paperless_mobile/core/config/hive/hive_config.dart';
+
+part 'user_account.g.dart';
+
+@HiveType(typeId: HiveTypeIds.userAccount)
+class UserAccount {
+  @HiveField(0)
+  final String serverUrl;
+  @HiveField(1)
+  final String username;
+  @HiveField(2)
+  final String? fullName;
+
+  UserAccount({
+    required this.serverUrl,
+    required this.username,
+    this.fullName,
+  });
+}