refactor: simplify MailImportWizard success view and adjust InboxDetailPage dropdown styling

paperless-frontend/src/pages/InboxDetailPage.tsx

@@ -1119,7 +1119,7 @@ export default function InboxDetailPage() {
           <SourceTag source={file.source} />
         </Space>
         <Dropdown.Button
-          style={{ marginLeft: 'auto' }}
+          style={{ marginLeft: 'auto', width: 'auto' }}
           type="primary"
           icon={<DownOutlined />}
           onClick={() => { if (canProcess) setWizardOpen(true); }}