Add test environment configuration and update Jest setup

- Created `.env.test.example` with test environment variables
- Updated `jest.config.cjs` to simplify configuration and improve test setup
- Added `jest.setup.ts` to load and configure test environment variables
- Updated test files to use dynamic test environment configuration
- Enhanced README.md with additional configuration details for testing

jest.setup.ts

@@ -0,0 +1,15 @@
+import { config } from 'dotenv';
+import { resolve } from 'path';
+
+// Load test environment variables
+const envFile = process.env.NODE_ENV === 'test' ? '.env.test' : '.env';
+config({ path: resolve(__dirname, envFile) });
+
+// Set default test environment variables if not provided
+process.env.TEST_HASS_HOST = process.env.TEST_HASS_HOST || 'http://localhost:8123';
+process.env.TEST_HASS_TOKEN = process.env.TEST_HASS_TOKEN || 'test_token';
+process.env.TEST_HASS_SOCKET_URL = process.env.TEST_HASS_SOCKET_URL || 'ws://localhost:8123/api/websocket';
+process.env.TEST_PORT = process.env.TEST_PORT || '3001';
+
+// Ensure test environment
+process.env.NODE_ENV = 'test';