feat: add env variables loading support and example

.env.example

@@ -0,0 +1,3 @@
+OPENAI_API_KEY=sk-123
+FINNHUB_API_KEY=
+GOOGLE_API_KEY=

main.py

@@ -1,5 +1,8 @@
 from tradingagents.graph.trading_graph import TradingAgentsGraph
 from tradingagents.default_config import DEFAULT_CONFIG
+from dotenv import load_dotenv
+
+load_dotenv()
 
 # Create a custom config
 config = DEFAULT_CONFIG.copy()

requirements.txt

@@ -24,3 +24,4 @@ rich
 questionary
 langchain_anthropic
 langchain-google-genai
+python-dotenv