style: unify recap+edit file figure styling — two-column grid dl, vertical spacing, admin-back-btn sizing, standardise file display and delete-to-trash SVG icons

app/src/Controllers/ThesisEditController.php

@@ -340,7 +340,7 @@ class ThesisEditController
         }
 
         // ── Cover image (outside transaction — filesystem op) ─────────────────
-        if (isset($post['remove_cover'])) {
+        if (!empty($post['remove_cover'])) {
             foreach ($existingFiles as $f) {
                 if ($f['file_type'] === 'cover') {
                     $this->db->deleteThesisFile((int)$f['id'], $thesisId);