feat: Added example environment variable files and test tool scripts

- Added a `.env.example` file with Etherscan API configuration instructions
- Updated `README.md` to provide the necessary tools for building the agent
- Added a `test_all_tools.py` script to thoroughly test all Etherscan MCP tools and generate reports

Author: FromCSUZhou

README.md

@@ -77,7 +77,7 @@ cp .env.example .env
 python test_all_tools.py
 ```
 
-This will test 39+ tools and generate detailed analysis for Agent development. See [`TESTING_SETUP.md`](TESTING_SETUP.md) for details.
+This will test all tools and generate detailed analysis for Agent development.
 
 ## Complete Tool Reference