🌐 feat: OpenRouter Web Search (#9853)

* 🌐 feat: OpenRouter Web Search

- Added tests for handling web_search parameter with OpenRouter in various scenarios.
- Implemented logic to manage web_search in modelOptions and addParams/dropParams.
- Ensured correct configuration of llmConfig and modelKwargs for OpenRouter, including handling of plugins.
- Improved overall integration of OpenRouter with OpenAI API, ensuring expected behavior across different configurations.

* chore: bump @librechat/agents to v2.4.81

api/package.json

@@ -49,7 +49,7 @@
     "@langchain/google-vertexai": "^0.2.13",
     "@langchain/openai": "^0.5.18",
     "@langchain/textsplitters": "^0.1.0",
-    "@librechat/agents": "^2.4.80",
+    "@librechat/agents": "^2.4.81",
     "@librechat/api": "*",
     "@librechat/data-schemas": "*",
     "@microsoft/microsoft-graph-client": "^3.0.7",