feat(credits): check-in details modal + history; oneline/tilt widgets

Add zibll-like check-in details remote modal (REST/AJAX), history
endpoint, header details link, and keep oneline posts + tilt showcase
widgets from this batch.

inc/helpers/user-center-renderers/credits-signin.php

@@ -30,9 +30,6 @@ if (class_exists('\AKSRT\Credits\Signin')) {
 	}, $signin_log));
 }
 
-if (empty($signin_dates)) {
-	return;
-}
 ?>
 <div class="uc-signin-calendar" style="margin-bottom:16px;">
 	<h4 class="uc-signin-calendar__title">