Replaces the Yahoo continuous-contract month parse with a volume-based
probe: walk the next 6 month codes via Yahoo's specific tickers
({PROD}{MONTH}{YY}.{EXCHANGE}) and pick the one with the highest recent
volume. Tracks the trader-standard "front month" definition and rolls
correctly even when the continuous (=F) feed lags expiry.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
