Paid JSON for stock-picker calls from financial newsletters and investing articles. Query params: optional `date=YYYY-MM-DD` for one UTC effective day, optional `period=latest` (same as default), optional `limit`. Default returns the latest UTC effective day with picks. Rows missing publication timestamps may use extractedAt for the effective day. Returns 404 when no picks exist for the day. The x402 amount is based on distinct attributed source posts returned.