Novashare 1.6.4

* Added new share button for Mistral AI.
* Made some minor adjustments to various network SVG viewBox values to be more consistent throughout the plugin.
* Changed hidden Pinterest images to use image thumbnails for the src attribute instead of the full image to save on overall load.
* Made some changes to the Novashare Details meta box UI to be more consistent and improve selected image visibility.
* Updated EDD plugin updater class to version 1.9.4.
* Fixed a PHP warning that would sometimes show up when checking for post short links.

* Added new AI share buttons for Claude and Google AI.
* Added new novashare_ai_network_text filter.
* Added support to set the Novashare license key via wp-config.php using the NOVASHARE_LICENSE_KEY constant.
* Removed Pocket share network from the plugin, as they have shut down.