Scan for assets with low Bollinger Band Width (squeeze detection). Works with crypto and stocks.

    This scans a whole EXCHANGE for squeezes (canonical name is exactly
    `bollinger_scan`; there is no "get_bollinger_band_analysis" tool). For
    the Bollinger read of ONE symbol, call `coin_analysis` instead.

    Example: bollinger_scan(exchange="BINANCE", timeframe="15m", bbw_threshold=0.008)

    Args:
        exchange: Exchange — crypto: KUCOIN, BINANCE, BYBIT, MEXC; stocks: EGX, BIST, NASDAQ, NYSE, BURSA, HKEX, SSE, SZSE, TWSE, TPEX
        timeframe: One of 5m, 15m, 1h, 4h, 1D, 1W, 1M. Typical squeeze thresholds: 15m→0.008, 1h→0.02, 4h→0.04, 1D→0.12
        bbw_threshold: Maximum BBW value to filter (default 0.04)
        limit: Number of rows to return (max 100)

    Returns ``list[dict]`` on success. On ANY failure returns a structured
    error envelope ``{"error": {"code": ..., "retryable": ...}}``.