fix: downloaded files should have _signed (#1149)

Modifies the generated filename for the downloaded PDF by appending
"_signed" to the base title.

## Changes Made

- Update the filename in the downloadFile function call to append
"_signed" to the baseTitle variable.

## Testing Performed

Tested the `downloadPDF` function locally to ensure that the downloaded
PDF file has the correct filename with "_signed" appended.

packages/lib/client-only/download-pdf.ts

@@ -18,7 +18,7 @@ export const downloadPDF = async ({ documentData, fileName }: DownloadPDFProps)
   const baseTitle = (fileName ?? 'document').replace(/\.pdf$/, '');
 
   downloadFile({
-    filename: `${baseTitle}.pdf`,
+    filename: `${baseTitle}_signed.pdf`,
     data: blob,
   });
 };