function prepareRagFolder() {
  const inputDir = path.join(__dirname, '../rag_input');
  const ingestedDir = path.join(inputDir, 'ingested');
  if (!fs.existsSync(inputDir)) {
    fs.mkdirSync(inputDir, { recursive: true });
  }
  if (!fs.existsSync(ingestedDir)) {
    fs.mkdirSync(ingestedDir, { recursive: true });
  }
  ragFolderReady = true;
}
Helper function to ensure the vector search index exists for RAG Boilerplate