When there are no transactions in the default display, the *Download
account activity* button is disabled. To avoid failing in this case, we
now navigate directly to the download page. This requires explicitly
selecting the credit card account from the dropdown list, as it is not
pre-filled when the page is loaded directly.
The `ntfyerror` context manager replaces `screenshot_failure` for
handling online banking interaction failures. It has several
advantages, notably:
* takes a screenshot of the browser page *before* logging out
* cleaner suppression of exceptions, with success tracking
* sends an `ntfy` message, with the screenshot attached
Dustin