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;
-    await navigator.clipboard.writeText(createdSecret);
-    setCopied(true);
-    toast.success("Secret kopiert");
+    try {
+      await navigator.clipboard.writeText(createdSecret);
+      setCopied(true);
+      toast.success("Secret kopiert");
+    } catch {
+      toast.error("Secret konnte nicht kopiert werden");
+    }
   }
 
   return (