Update README and implement device listing tool

- Updated prerequisites in README.md to require Node.js 20.10.0 and NPM instead of Yarn.
- Changed repository clone URL to reflect the new username.
- Introduced a new 'list_devices' tool in src/index.ts to fetch and display all available Home Assistant devices, enhancing interaction capabilities.
- Updated README.md to include detailed usage instructions for the new device listing and control tools.
- Refactored environment variable names for consistency and clarity.

src/__tests__/context.test.ts

@@ -4,6 +4,7 @@ import { DomainSchema } from '../schemas.js';
 // Define types for tool and server
 interface Tool {
     name: string;
+    description: string;
     execute: (params: any) => Promise<any>;
     parameters: z.ZodType<any>;
 }