feat(useragent): added connection info setup screen

useragent/lib/features/arbiter_url.dart

@@ -0,0 +1,56 @@
+import 'dart:convert';
+
+class ArbiterUrl {
+  const ArbiterUrl({
+    required this.host,
+    required this.port,
+    required this.caCert,
+    this.bootstrapToken,
+  });
+
+  final String host;
+  final int port;
+  final List<int> caCert;
+  final String? bootstrapToken;
+
+  static const _scheme = 'arbiter';
+  static const _certQueryKey = 'cert';
+  static const _bootstrapTokenQueryKey = 'bootstrap_token';
+
+  static ArbiterUrl parse(String value) {
+    final uri = Uri.tryParse(value);
+    if (uri == null || uri.scheme != _scheme) {
+      throw const FormatException("Invalid URL scheme, expected 'arbiter://'");
+    }
+
+    if (uri.host.isEmpty) {
+      throw const FormatException('Missing host in URL');
+    }
+
+    if (!uri.hasPort) {
+      throw const FormatException('Missing port in URL');
+    }
+
+    final cert = uri.queryParameters[_certQueryKey];
+    if (cert == null || cert.isEmpty) {
+      throw const FormatException("Missing 'cert' query parameter in URL");
+    }
+
+    final decodedCert = _decodeCert(cert);
+
+    return ArbiterUrl(
+      host: uri.host,
+      port: uri.port,
+      caCert: decodedCert,
+      bootstrapToken: uri.queryParameters[_bootstrapTokenQueryKey],
+    );
+  }
+
+  static List<int> _decodeCert(String cert) {
+    try {
+      return base64Url.decode(base64Url.normalize(cert));
+    } on FormatException catch (error) {
+      throw FormatException("Invalid base64 in 'cert' query parameter: ${error.message}");
+    }
+  }
+}

useragent/lib/features/connection/connection.dart

@@ -0,0 +1,3 @@
+
+
+class Connection {}

useragent/lib/features/pk_manager.dart

@@ -1,6 +1,3 @@
-
-import 'package:flutter/services.dart';
-
 enum KeyAlgorithm {
   rsa, ecdsa, ed25519
 }
@@ -16,4 +13,4 @@ abstract class KeyHandle {
 abstract class KeyManager {
   Future<KeyHandle?> get();
   Future<KeyHandle> create();
-}
+}

useragent/lib/features/server_info_storage.dart

@@ -0,0 +1,67 @@
+import 'dart:convert';
+
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+
+class StoredServerInfo {
+  const StoredServerInfo({
+    required this.address,
+    required this.port,
+    required this.caCertFingerprint,
+  });
+
+  final String address;
+  final int port;
+  final String caCertFingerprint;
+
+  Map<String, dynamic> toJson() => {
+    'address': address,
+    'port': port,
+    'caCertFingerprint': caCertFingerprint,
+  };
+
+  factory StoredServerInfo.fromJson(Map<String, dynamic> json) {
+    return StoredServerInfo(
+      address: json['address'] as String,
+      port: json['port'] as int,
+      caCertFingerprint: json['caCertFingerprint'] as String,
+    );
+  }
+}
+
+abstract class ServerInfoStorage {
+  Future<StoredServerInfo?> load();
+  Future<void> save(StoredServerInfo serverInfo);
+  Future<void> clear();
+}
+
+class SecureServerInfoStorage implements ServerInfoStorage {
+  static const _storageKey = 'server_info';
+
+  const SecureServerInfoStorage();
+
+  static const _storage = FlutterSecureStorage();
+
+  @override
+  Future<StoredServerInfo?> load() async {
+    final rawValue = await _storage.read(key: _storageKey);
+    if (rawValue == null) {
+      return null;
+    }
+
+    final decoded = jsonDecode(rawValue) as Map<String, dynamic>;
+    return StoredServerInfo.fromJson(decoded);
+  }
+
+  @override
+  Future<void> save(StoredServerInfo serverInfo) {
+    return _storage.write(
+      key: _storageKey,
+      value: jsonEncode(serverInfo.toJson()),
+    );
+  }
+
+  @override
+  Future<void> clear() {
+    return _storage.delete(key: _storageKey);
+  }
+}