Crowdsignal shortcode not working

## Steps to Reproduce
1. Create a poll
2. Add the shortcode to a page on your site, e.g. [crowdsignal poll='15546239']

## What I expected

The poll would display on the page.

## What happened instead

The poll is not displayed.

## PHP, WordPress, Crowdsignal versions

php_version: 8.2.29 64bit
WP: 6.8.2
Crowdsignal Polls & Ratings: version: 3.1.2

## Additional context
Reported in 10228414-zd-a8c

Start by reproducing [crowdsignal poll='15546239'] on WordPress 6.8.2 with PHP 8.2.29 and Crowdsignal Polls & Ratings 3.1.2, then trace the plugin's shortcode handling. Done means the poll renders on the page as expected, with the relevant behavior covered by the plugin's existing checks if available.

Written by the indexing model from the issue text.