Detect coins with volume breakout + price breakout.

    Args:
        exchange: Exchange name like KUCOIN, BINANCE, BYBIT, MEXC, etc.
        timeframe: One of 5m, 15m, 1h, 4h, 1D, 1W, 1M
        volume_multiplier: How many times the volume should be above normal level (default 2.0)
        price_change_min: Minimum price change percentage (default 3.0)
        limit: Number of rows to return (max 50)

    Returns ``list[dict]`` on success, or an error envelope on total upstream
    failure (``{"error": {"code": "ALL_BATCHES_FAILED", ...}}``). The empty
    list now strictly means "no matches today"; rate-limit cliffs surface
    explicitly.