TF-3826 Try guessing webfinger when dns look up fail

test/features/login/domain/model/oidc_guessing_origin_test.dart

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+import 'package:flutter_test/flutter_test.dart';
+import 'package:tmail_ui_user/features/login/domain/model/oidc_guessing_origin.dart';
+
+void main() {
+  group('OidcGuessingOrigin enum', () {
+    test('url() returns correct URL for empty origin', () {
+      const email = 'user@example.com';
+      const origin = OidcGuessingOrigin.empty;
+      expect(origin.url(email), 'https://example.com');
+    });
+
+    test('url() returns correct URL for autoDiscover origin', () {
+      const email = 'user@example.com';
+      const origin = OidcGuessingOrigin.autoDiscover;
+      expect(origin.url(email), 'https://autodiscover.example.com');
+    });
+
+    test('url() returns correct URL for jmap origin', () {
+      const email = 'user@example.com';
+      const origin = OidcGuessingOrigin.jmap;
+      expect(origin.url(email), 'https://jmap.example.com');
+    });
+
+    test('url() throws error for invalid email', () {
+      const email = 'invalid_email@@example.com';
+      const origin = OidcGuessingOrigin.empty;
+      expect(() => origin.url(email), throwsArgumentError);
+    });
+    
+    test('url() returns correct URL for jmap origin with quoted local part', () {
+      const email = '"user"@example.com';
+      const origin = OidcGuessingOrigin.jmap;
+      expect(origin.url(email), 'https://jmap.example.com');
+    });
+    
+    test('url() returns correct URL for jmap origin with quoted local part containing @', () {
+      const email = '"user@local"@example.com';
+      const origin = OidcGuessingOrigin.jmap;
+      expect(origin.url(email), 'https://jmap.example.com');
+    });
+  });
+}