refactor: Enhance environment configuration and loading mechanism

- Implement flexible environment variable loading strategy
- Add support for environment-specific and local override configuration files
- Create new `loadEnv.ts` module for dynamic environment configuration
- Update configuration loading in multiple config files
- Remove deprecated `.env.development.template`
- Add setup script for environment validation
- Improve WebSocket error handling and client configuration

.gitignore

@@ -71,7 +71,7 @@ coverage/
 # Environment files
 .env
 .env.*
-!.env.*.template
+!.env.example
 
 .cursor/
 .cursor/*