refactor(sentry): standardize exceptions to prevent Sentry minification

lib/features/composer/domain/exceptions/compose_email_exception.dart

@@ -1,3 +1,15 @@
-class SendingEmailCanceledException implements Exception {}
+import 'package:core/domain/exceptions/app_base_exception.dart';
 
-class SavingEmailToDraftsCanceledException implements Exception {}
+class SendingEmailCanceledException extends AppBaseException {
+  SendingEmailCanceledException([super.message]);
+
+  @override
+  String get exceptionName => 'SendingEmailCanceledException';
+}
+
+class SavingEmailToDraftsCanceledException extends AppBaseException {
+  SavingEmailToDraftsCanceledException([super.message]);
+
+  @override
+  String get exceptionName => 'SavingEmailToDraftsCanceledException';
+}