Route error reports + tx-failed support contact to support@such.software

Cake's email was hardcoded as the recipient for the 'Send error report'
flow in ExceptionHandler and as the contact in the TransactionCommitFailed
user-facing message. Anyone tapping Send would have mailed their wallet
metadata to Cake's support team. Repointed both to support@such.software.

lib/utils/exception_handler.dart

@@ -90,7 +90,7 @@ class ExceptionHandler {
 
       final MailOptions mailOptions = MailOptions(
         subject: 'Mobile App Issue',
-        recipients: ['support@cakewallet.com'],
+        recipients: ['support@such.software'],
         attachments: [_file!.path],
       );