Gonzo release

A weird title to get your attention. 😎

chore: bumped manifest browser extension version to 1.2.2
chore: cleaned up icon64 with correct PNG header
chore: dist folder is cleanded before start and build scripts run now
chore: converted content script to TypeScript #6 closes #5
fix: fixed issue where user was prompted more than once per Tweet to add alt text #4 closes #3

Fixed Missing Alt Text Detection

Previously, a click event handler for the Tweet button was being used, but something changed in the Twitter app. Now a mouse down event handler is used to detect missing alt text for images.