Use dedicated birthday entry controls (#67)

frontend/app/lib/kyc/profile.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 
 import 'package:sxchnge_kyc/sxchnge_kyc.dart';
 
+import 'birth.dart';
 import 'country.dart';
 
 import '../generated/i18n/app_localizations.dart';
@@ -37,17 +38,11 @@ class ProfileForm extends StatelessWidget {
           onChanged: (value) => update(name: value),
         ),
         const SizedBox(height: 16),
-        TextFormField(
+        BirthField(
           key: const ValueKey('kyc-birth'),
-          initialValue: p.profile.dateOfBirth,
+          value: p.profile.dateOfBirth,
           enabled: !p.busy,
-          keyboardType: TextInputType.datetime,
-          autofillHints: const [AutofillHints.birthday],
-          decoration: InputDecoration(
-            labelText: l.kycBirth,
-            helperText: l.kycBirthHelp,
-          ),
-          onChanged: (value) => update(birth: value.trim()),
+          onChanged: (value) => update(birth: value),
         ),
         const SizedBox(height: 16),
         CountryField(