Add @ prefix to Follow-Block (#694)

Author: pfefferle

includes/class-blocks.php

@@ -78,6 +78,12 @@ public static function render_follow_me_block( $attrs ) {
 				array( 'icon', 'name', 'webfinger' )
 			);
 		}
+
+		// add `@` prefix if it's missing
+		if ( '@' !== substr( $attrs['profileData']['webfinger'], 0, 1 ) ) {
+			$attrs['profileData']['webfinger'] = '@' . $attrs['profileData']['webfinger'];
+		}
+
 		$wrapper_attributes = get_block_wrapper_attributes(
 			array(
 				'aria-label' => __( 'Follow me on the Fediverse', 'activitypub' ),