fix: handle document download and clipboard copy failures

Two unguarded async calls silently swallowed errors: document download
used a bare "void downloadDocument(...)" with no catch, so a failed
download (network error, expired session) did nothing visible; the
webhook secret copy button had no try/catch around
navigator.clipboard.writeText, which can throw on denied permission or
an insecure context. Both now show a toast on failure.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

ApiCore-Frontend/src/app/(app)/settings/automation/create-webhook-dialog.tsx

@@ -75,9 +75,13 @@ export function CreateWebhookDialog() {
 
   async function copySecret() {
     if (!createdSecret) return;
+    try {
       await navigator.clipboard.writeText(createdSecret);
       setCopied(true);
       toast.success("Secret kopiert");
+    } catch {
+      toast.error("Secret konnte nicht kopiert werden");
+    }
   }
 
   return (

ApiCore-Frontend/src/components/document-upload-card.tsx

@@ -129,7 +129,11 @@ export function DocumentUploadCard({
               <Button
                 size="sm"
                 variant="outline"
-                onClick={() => void downloadDocument(document.id, document.fileName)}
+                onClick={() => {
+                  downloadDocument(document.id, document.fileName).catch(() =>
+                    toast.error("Datei konnte nicht heruntergeladen werden"),
+                  );
+                }}
               >
                 Herunterladen
               </Button>