📦 chore: Remove @langchain/community & Related Legacy Code (#10375)

* chore: remove `@langchain/community` dependency

* refactor: remove SerpAPI integration and update related imports

* chore: remove legacy code with unnecessary dependencies

* chore: cleanup packages

* chore: cleanup packages

* chore: update openai dependency version to 5.10.1

* chore: add back @librechat/agents dependency

* chore: downgrade openai dependency from 5.10.1 to 5.8.2

* Remove dependency on @librechat/agents from the API package

* chore: add @librechat/agents dependency to the API package

* fix: add useLegacyContent property to RunAgent type and propagate it in createRun function

* chore: remove openai dependency version 5.10.1 from package.json

.env.example

@@ -298,10 +298,6 @@ GOOGLE_CSE_ID=
 #-----------------
 YOUTUBE_API_KEY=
 
-# SerpAPI
-#-----------------
-SERPAPI_API_KEY=
-
 # Stable Diffusion
 #-----------------
 SD_WEBUI_URL=http://host.docker.internal:7860