🔄 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/typedefs.js

@@ -43,6 +43,60 @@
  * @memberof typedefs
  */
 
+/**
+ * @exports Graph
+ * @typedef {import('@librechat/agents').Graph} Graph
+ * @memberof typedefs
+ */
+
+/**
+ * @exports StandardGraph
+ * @typedef {import('@librechat/agents').StandardGraph} StandardGraph
+ * @memberof typedefs
+ */
+
+/**
+ * @exports EventHandler
+ * @typedef {import('@librechat/agents').EventHandler} EventHandler
+ * @memberof typedefs
+ */
+
+/**
+ * @exports ModelEndData
+ * @typedef {import('@librechat/agents').ModelEndData} ModelEndData
+ * @memberof typedefs
+ */
+
+/**
+ * @exports ToolEndData
+ * @typedef {import('@librechat/agents').ToolEndData} ToolEndData
+ * @memberof typedefs
+ */
+
+/**
+ * @exports ToolEndCallback
+ * @typedef {import('@librechat/agents').ToolEndCallback} ToolEndCallback
+ * @memberof typedefs
+ */
+
+/**
+ * @exports ChatModelStreamHandler
+ * @typedef {import('@librechat/agents').ChatModelStreamHandler} ChatModelStreamHandler
+ * @memberof typedefs
+ */
+
+/**
+ * @exports ContentAggregator
+ * @typedef {import('@librechat/agents').ContentAggregatorResult['aggregateContent']} ContentAggregator
+ * @memberof typedefs
+ */
+
+/**
+ * @exports GraphEvents
+ * @typedef {import('@librechat/agents').GraphEvents} GraphEvents
+ * @memberof typedefs
+ */
+
 /**
  * @exports AgentRun
  * @typedef {import('@librechat/agents').Run} AgentRun
@@ -97,12 +151,6 @@
  * @memberof typedefs
  */
 
-/**
- * @exports ToolEndData
- * @typedef {import('@librechat/agents').ToolEndData} ToolEndData
- * @memberof typedefs
- */
-
 /**
  * @exports BaseMessage
  * @typedef {import('@langchain/core/messages').BaseMessage} BaseMessage