redesigned payment page + a lot of fixes

frontend/pweb/lib/providers/signup_confirmation.dart

@@ -0,0 +1,91 @@
+import 'dart:async';
+
+import 'package:flutter/foundation.dart';
+
+import 'package:pshared/models/auth/probe_result.dart';
+import 'package:pshared/provider/account.dart';
+
+
+class SignupConfirmationProvider extends ChangeNotifier {
+  SignupConfirmationProvider({
+    required AccountProvider accountProvider,
+    Duration pollInterval = const Duration(seconds: 10),
+  }) : _accountProvider = accountProvider,
+       _pollInterval = pollInterval;
+
+  final AccountProvider _accountProvider;
+  final Duration _pollInterval;
+
+  Timer? _pollTimer;
+  bool _isChecking = false;
+  bool _isAuthorized = false;
+
+  String? _email;
+  String? _password;
+  String? _locale;
+
+  bool get isAuthorized => _isAuthorized;
+  bool get isChecking => _isChecking;
+
+  void startPolling({
+    required String email,
+    required String password,
+    required String locale,
+  }) {
+    final trimmedEmail = email.trim();
+    final trimmedPassword = password.trim();
+    final trimmedLocale = locale.trim();
+    if (trimmedEmail.isEmpty || trimmedPassword.isEmpty || trimmedLocale.isEmpty) {
+      return;
+    }
+
+    _email = trimmedEmail;
+    _password = trimmedPassword;
+    _locale = trimmedLocale;
+
+    _pollTimer?.cancel();
+    _pollTimer = Timer.periodic(_pollInterval, (_) => _probeAuthorization());
+    _probeAuthorization();
+  }
+
+  void stopPolling() {
+    _pollTimer?.cancel();
+    _pollTimer = null;
+  }
+
+  @override
+  void dispose() {
+    _pollTimer?.cancel();
+    super.dispose();
+  }
+
+  Future<void> _probeAuthorization() async {
+    if (_isChecking || _isAuthorized) return;
+    final email = _email;
+    final password = _password;
+    final locale = _locale;
+    if (email == null || password == null || locale == null) return;
+
+    _setChecking(true);
+    try {
+      final result = await _accountProvider.probeAuthorization(
+        email: email,
+        password: password,
+        locale: locale,
+      );
+      if (result == AuthProbeResult.authorized) {
+        _isAuthorized = true;
+        stopPolling();
+        notifyListeners();
+      }
+    } finally {
+      _setChecking(false);
+    }
+  }
+
+  void _setChecking(bool value) {
+    if (_isChecking == value) return;
+    _isChecking = value;
+    notifyListeners();
+  }
+}