fix: address ESLint errors (unused imports, missing newline at EOF)

- src/index.test.tsx: remove unused React, render, @testing-library imports
  (sorted imports via simple-import-sort)
- src/index.tsx: add trailing newline (eol-last fix)

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

src/index.tsx

@@ -73,4 +73,4 @@ registerRoute({
       <ArgoCDStubView />
     </ArgoCDErrorBoundary>
   ),
-});
+});