Fix COPY button on API Keys page

lt.copy() does not exist — the correct API is lt.clipboard.copy().
Also added ok-check since clipboardCopy() returns a boolean promise,
not a rejection on failure.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

views/admin/ApiKeysView.php

@@ -175,8 +175,9 @@ document.getElementById('generateKeyForm').addEventListener('submit', function (
 
 function copyApiKey() {
     var val = document.getElementById('newKeyValue').value;
-    lt.copy(val).then(function () {
-        lt.toast.success('Copied to clipboard!');
+    lt.clipboard.copy(val).then(function (ok) {
+        if (ok) lt.toast.success('Copied to clipboard!');
+        else lt.toast.error('Copy failed — select the key manually');
     }).catch(function () {
         lt.toast.error('Copy failed — select the key manually');
     });