Add environment example

.env.example

@@ -0,0 +1,9 @@
+APP_NAME=Trade Autopilot
+APP_ENV=local
+TRADE_MODE=demo
+ENABLE_LIVE_TRADING=false
+DEMO_INITIAL_BALANCE=10000
+DEMO_QUOTE_ASSET=USDT
+COINEX_API_BASE=https://api.coinex.com/v2
+COINEX_WS_SPOT=wss://socket.coinex.com/v2/spot
+DEFAULT_MARKET=BTCUSDT