Initial commit: LangGraph chatbot with shell tool capabilities

- Add basic LangGraph chatbot implementation with OpenAI GPT-4
- Include shell tool integration for system command execution
- Set up project with uv package manager
- Add comprehensive README with setup instructions
- Include proper .gitignore for Python projects

.env.example

@@ -0,0 +1,11 @@
+# Environment Variables Template
+# Copy this file to .env and fill in your actual values
+
+# OpenAI API Key - Get from https://platform.openai.com/api-keys
+OPENAI_API_KEY=your-openai-api-key-here
+
+# Optional: LangSmith API Key for debugging and monitoring
+# LANGSMITH_API_KEY=your-langsmith-api-key-here
+# LANGSMITH_TRACING=true
+
+TAVILY_API_KEY=your-tavily-api-key-here