paramètres: fix logs Copier button scrolling out of view on horizontal scroll

Wrap .log-output and the copy button in a .log-output-wrapper div
with position:relative, so the button sits outside the overflow-x:auto
scroll container and stays fixed at the top-right corner.

app/templates/admin/partials/system-log-panel.php

@@ -47,14 +47,16 @@
     <div class="log-empty">Le fichier journal est vide.</div>
 
 <?php else: ?>
-    <div class="log-output" id="log-output" role="log" aria-live="off" aria-label="Contenu du journal">
+    <div class="log-output-wrapper">
         <button class="btn btn--secondary btn--sm log-copy-btn" id="log-copy-btn" type="button" title="Copier le contenu"
                 onclick="copyLogContent(this);return false">
             Copier
         </button>
+        <div class="log-output" id="log-output" role="log" aria-live="off" aria-label="Contenu du journal">
         <?php foreach ($logLines as $i => $line): ?>
         <span class="log-line <?= SystemController::logLineClass($line) ?>"
               data-n="<?= count($logLines) - $i ?>"><?= htmlspecialchars($line, ENT_QUOTES | ENT_SUBSTITUTE) ?></span>
         <?php endforeach; ?>
+        </div>
     </div>
 <?php endif; ?>