Add Binance Testnet exchange gateway

config.example.toml

@@ -5,11 +5,27 @@ model = "deepseek-flash"
 thinking = true
 max_tool_rounds = 256
 
+# Choose exactly one provider for this process. Binance is permanently restricted
+# to its Spot and USDⓈ-M Futures Testnet endpoints in application code.
+[exchange]
+provider = "binance" # binance | bybit
+
 [bybit]
 api_key = "replace-me"
 api_secret = "replace-me"
 settle_coin = "USDT"
 
+[binance.spot]
+# Create these keys at https://testnet.binance.vision/ . They are not shared
+# with the USDⓈ-M Futures demo environment below.
+api_key = "replace-me"
+api_secret = "replace-me"
+
+[binance.usdm]
+# Create these keys in the USDⓈ-M Futures Testnet/Demo environment.
+api_key = "replace-me"
+api_secret = "replace-me"
+
 [telegram]
 api_id = 123456
 api_hash = "replace-me"