Add Ticker24h support: hourly market snapshots with USD-normalized volume filtering

gateway/knowledge/usage-examples.md

@@ -92,6 +92,61 @@ All columns below are fully populated for Binance data. Other exchanges provide
 - `"ticker"` - Market identifier
 - `"period_seconds"` - Period in seconds
 
+## Building a Scanner Universe with get_ticker_24h
+
+**Always pre-filter symbols before fetching OHLC data for scanners.** Fetching OHLC for all ~1800 Binance symbols would exhaust the 2M-bar per-script budget instantly. Use `get_ticker_24h` to get a ranked list of all symbols for free (no OHLC budget cost), then run per-symbol analysis only on the filtered set.
+
+```python
+from dexorder.api import get_api
+import asyncio
+
+api = get_api()
+
+# Get top 50 most liquid Binance spot symbols (no OHLC budget used)
+universe = asyncio.run(api.data.get_ticker_24h(
+    "BINANCE",
+    limit=50,
+    market_type="spot",
+    min_std_quote_volume=10_000_000  # $10M+ daily volume
+))
+print(f"Universe: {len(universe)} symbols")
+print(universe[["ticker", "std_quote_volume", "price_change_pct"]].head(10))
+
+# Now fetch OHLC only for these symbols
+tickers = universe["ticker"].tolist()
+results = {}
+for ticker in tickers:
+    df = asyncio.run(api.data.historical_ohlc(
+        ticker=ticker,
+        period_seconds=3600,
+        start_time="2024-01-01",
+        end_time="2025-01-01",
+        extra_columns=["volume"]
+    ))
+    print(f"[Data] {ticker}: {len(df)} bars")
+    results[ticker] = df
+```
+
+### get_ticker_24h filter parameters
+
+```python
+# All BTC pairs on Binance (spot + perp)
+df = asyncio.run(api.data.get_ticker_24h("BINANCE", base_asset_contains="BTC"))
+
+# Top 100 perp markets with at least $50M daily volume
+df = asyncio.run(api.data.get_ticker_24h(
+    "BINANCE",
+    limit=100,
+    market_type="perp",
+    min_std_quote_volume=50_000_000
+))
+
+# All Coinbase symbols (for a cross-exchange scan)
+df = asyncio.run(api.data.get_ticker_24h("COINBASE"))
+```
+
+The returned DataFrame is sorted by `std_quote_volume` (USD-normalized volume) descending. Symbols without a USD conversion path have `std_quote_volume = NaN` and appear last. Columns: `ticker`, `exchange_id`, `base_asset`, `quote_asset`, `last_price`, `price_change_pct`, `quote_volume_24h`, `std_quote_volume`, `bid_price`, `ask_price`, `open_24h`, `high_24h`, `low_24h`, `volume_24h`, `num_trades`, `timestamp_ms`.
+
 ## Using the Charting API
 
 The charting API provides styled financial charts with OHLC candlesticks and technical indicators.