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

.env.test.example

@@ -0,0 +1,11 @@
+# Test Environment Configuration
+
+# Home Assistant Test Instance
+TEST_HASS_HOST=http://localhost:8123
+TEST_HASS_TOKEN=test_token
+TEST_HASS_SOCKET_URL=ws://localhost:8123/api/websocket
+
+# Test Server Configuration
+TEST_PORT=3001
+NODE_ENV=test
+DEBUG=false