test: Refactor WebSocket and speech tests for improved mocking and reliability

- Update WebSocket client test suite with more robust mocking
- Enhance SpeechToText test coverage with improved event simulation
- Simplify test setup and reduce complexity of mock implementations
- Remove unnecessary test audio files and cleanup test directories
- Improve error handling and event verification in test scenarios

package.json

@@ -55,7 +55,8 @@
     "husky": "^9.0.11",
     "prettier": "^3.2.5",
     "supertest": "^6.3.3",
-    "uuid": "^11.0.5"
+    "uuid": "^11.0.5",
+    "@types/bun": "latest"
   },
   "engines": {
     "bun": ">=1.0.0"