Get TTS-preprocessed report text

Returns the report content preprocessed for text-to-speech synthesis. Applies pronunciation normalization for acronyms, currency, and percentages; strips HTML and Markdown; and adds branding intro/outro text. Cartesia TTS generation uses this pipeline. Requires the `reports:read` scope. Supports x402 pay-per-request. Requests with a valid Bearer token use API-key authentication. Without a Bearer API key, start the x402 flow from the `402 Payment Required` response and `PAYMENT-REQUIRED` header; retry with `PAYMENT-SIGNATURE`.