verification before payment and email fixes

frontend/pweb/lib/pages/login/form.dart

@@ -15,6 +15,7 @@ import 'package:pweb/widgets/password/hint/short.dart';
 import 'package:pweb/widgets/password/password.dart';
 import 'package:pweb/widgets/username.dart';
 import 'package:pweb/widgets/vspacer.dart';
+import 'package:pweb/controllers/email.dart';
 import 'package:pweb/utils/error/snackbar.dart';
 import 'package:pweb/services/posthog.dart';
 
@@ -31,12 +32,11 @@ class LoginForm extends StatefulWidget {
 }
 
 class _LoginFormState extends State<LoginForm> {
-  final TextEditingController _usernameController = TextEditingController();
+  final EmailFieldController _emailController = EmailFieldController();
   final TextEditingController _passwordController = TextEditingController();
   final _formKey = GlobalKey<FormState>();
 
   // ValueNotifiers for validation state
-  final ValueNotifier<bool> _isUsernameAcceptable = ValueNotifier<bool>(false);
   final ValueNotifier<bool> _isPasswordAcceptable = ValueNotifier<bool>(false);
 
   @override
@@ -44,8 +44,7 @@ class _LoginFormState extends State<LoginForm> {
     super.initState();
     final initialEmail = widget.initialEmail?.trim();
     if (initialEmail != null && initialEmail.isNotEmpty) {
-      _usernameController.text = initialEmail;
-      _isUsernameAcceptable.value = true;
+      _emailController.setText(initialEmail);
     }
   }
 
@@ -54,7 +53,7 @@ class _LoginFormState extends State<LoginForm> {
 
     try {
       final outcome = await provider.login(
-        email: _usernameController.text,
+        email: _emailController.text,
         password: _passwordController.text,
         locale: context.read<LocaleProvider>().locale.languageCode,
       );
@@ -74,9 +73,8 @@ class _LoginFormState extends State<LoginForm> {
 
   @override
   void dispose() {
-    _usernameController.dispose();
+    _emailController.dispose();
     _passwordController.dispose();
-    _isUsernameAcceptable.dispose();
     _isPasswordAcceptable.dispose();
     super.dispose();
   }
@@ -93,8 +91,7 @@ class _LoginFormState extends State<LoginForm> {
           const LoginHeader(),
           const VSpacer(multiplier: 1.5),
           UsernameField(
-            controller: _usernameController,
-            onValid: (isValid) => _isUsernameAcceptable.value = isValid,
+            controller: _emailController,
           ),
           VSpacer(),
           defaulRulesPasswordField(
@@ -105,7 +102,7 @@ class _LoginFormState extends State<LoginForm> {
           ),
           VSpacer(multiplier: 2.0),
           ValueListenableBuilder<bool>(
-            valueListenable: _isUsernameAcceptable,
+            valueListenable: _emailController.isValid,
             builder: (context, isUsernameValid, child) => ValueListenableBuilder<bool>(
               valueListenable: _isPasswordAcceptable,
               builder: (context, isPasswordValid, child) => ButtonsRow(