Summary stat strip for the Whale Alerts page (4 cards).

Reads ONLY from smart_trades_recent — the rolling 48h table of smart-whale trades (>= $1K) maintained by update_smart_trades_recent.py. Zero scans of trades_apr2026_plus, so it stays a sub-10ms query and adds no load to the live DB. The 48h retention is exactly what powers the "vs previous 24h" delta (current window vs the equal-length window before it).

Returns: total alerts (+delta% vs prev window), total USD volume, biggest single trade (with market for click-through), most active whale.

Caveat: smart_trades_recent has a $1K floor while the feed shows from $500, so these totals count from $1K. Acceptable for an overview strip; the delta is only meaningful once the table holds a full 48h (it does as of 21.05).