Add a translation assistant to the panel

Each field's original sits beside the field to write, and a translation that
fell behind shows what the original said when it was translated and what it
says now, word by word.

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

lang/en/panel.php

@@ -144,6 +144,38 @@ return [
         'select_all' => 'Select all',
     ],
 
+    'translate' => [
+        'title' => 'Translations',
+        'title_for' => ':title in :language',
+        'action' => 'Translate',
+        'pending' => 'To translate',
+        'pending_hint' => 'What is still to be written in a language (blue) or fell behind because the original changed afterwards (amber).',
+        'nothing' => 'Everything is translated and up to date.',
+        'translate_into' => 'Translate into :language',
+        'update_in' => 'Update :language (since :since)',
+        'changed' => 'Changed in the original:',
+        'stale_since' => 'The original changed on :date, after it was translated.',
+        'save' => 'Save in :language',
+        'saved' => 'Translation saved',
+        'back' => 'Back to the list',
+        'columns' => [
+            'record' => 'Content',
+            'languages' => 'Languages',
+        ],
+        'fields' => [
+            'title' => 'Title',
+            'excerpt' => 'Excerpt',
+            'body' => 'Content',
+            'meta_title' => 'SEO title',
+            'meta_description' => 'SEO description',
+            'tagline' => 'Tagline',
+            'description' => 'Description',
+            'decisions' => 'Decisions',
+            'postmortem' => 'Postmortem',
+            'what_you_get' => 'What you get',
+        ],
+    ],
+
     'replies' => [
         'empty_template' => 'The template has no text in the language of this submission.',
         'heading' => 'Reply to :name',