Reintroduce TFE duration metadata: DB columns, form fields, controllers, views, and migration

Add 'unsafe-eval' to CSP script-src directives (htmx requires Function())

app/templates/partials/form/fichiers-fragment.php

@@ -89,7 +89,7 @@ $websiteLabel = htmlspecialchars($_POST['website_label'] ?? '');
                    data-queue-type="cover"
                    data-existing-files='<?= htmlspecialchars(json_encode($existingFilesJsonForCover ?? []), ENT_QUOTES) ?>'
                    aria-describedby="couverture-hint">
-            <small id="couverture-hint">JPG, PNG ou WEBP. Format 4:3 recommandé. Max 20 MB.</small>
+            <small id="couverture-hint">JPG, PNG ou WEBP. Format 4:3 recommandé (ex. 1200 × 900 px). Max 20 MB.</small>
         </div>
         <?php if ($editMode): ?>
         <button type="button" class="btn btn--sm btn--ghost file-browser-trigger"