🔄 fix: Assistants Endpoint & Minor Issues (#7274)

* 🔄 fix: Include usage in stream options for OpenAI and Azure endpoints

* fix: Agents support for Azure serverless endpoints

* fix: Refactor condition for assistants and azureAssistants endpoint handling

* AWS Titan via Bedrock: model doesn't support system messages, Closes #6456

* fix: Add EndpointSchemaKey type to endpoint parameters in buildDefaultConvo and ensure assistantId is always defined

* fix: Handle new conversation state for assistants endpoint in finalHandler

* fix: Add spec and iconURL parameters to `saveAssistantMessage` to persist modelSpec fields

* fix: Handle assistant unlinking even if no valid files to delete

* chore: move type definitions from callbacks.js to typedefs.js

* chore: Add StandardGraph typedef to typedefs.js

* chore: Update parameter type for graph in ModelEndHandler to StandardGraph

---------

Co-authored-by: Andres Restrepo <andres@enric.ai>

api/server/controllers/assistants/chatV2.js

@@ -428,6 +428,8 @@ const chatV2 = async (req, res) => {
       thread_id,
       model: assistant_id,
       endpoint,
+      spec: endpointOption.spec,
+      iconURL: endpointOption.iconURL,
     };
 
     sendMessage(res, {