Add an editorial calendar to the panel

A month of publications, scheduled dates, content coming off the site, and
calls opening and closing, each linked to its form.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lang/en/panel.php

@@ -144,6 +144,27 @@ return [
         'select_all' => 'Select all',
     ],
 
+    'calendar' => [
+        'title' => 'Editorial calendar',
+        'legend' => 'Legend',
+        'previous' => 'Previous month',
+        'next' => 'Next month',
+        'today' => 'Today',
+        'events' => [
+            'published' => 'Published',
+            'scheduled' => 'Scheduled',
+            'unpublishes' => 'Comes off the site',
+            'opens' => 'Opens',
+            'closes' => 'Closes',
+        ],
+        'types' => [
+            'pages' => 'Page',
+            'projects' => 'Project',
+            'services' => 'Service',
+            'calls' => 'Call',
+        ],
+    ],
+
     'expiring' => [
         'heading' => 'Coming up',
         'description' => 'Calls closing and content coming off the site in the next :days days.',