Added support for asynchronous processing for chat

paths/chat/chat.yml

@@ -27,6 +27,15 @@ post:
                   content: "Can you explain polymorphism?"
               configuration: null
 
+          minimalChatAsynchronous:
+            summary: Asynchronous minimal chat request
+            value:
+              messages:
+                - role: USER
+                  content: "Can you explain polymorphism?"
+              configuration: null
+              callbackUrl: "https://learning-platform.example.com/hooks/chat-result"
+
           chatWithLlmConfig:
             summary: Chat request with optional LLM configuration
             value:

paths/chat/schemas/ChatRequest.yml

@@ -26,6 +26,15 @@ properties:
       - "null"
     description: Optional educational context (e.g., course material, task context).
     additionalProperties: true
+  callbackUrl:
+    type:
+      - string
+      - "null"
+    format: uri
+    description: >
+      Optional HTTPS callback URL for asynchronous processing. If provided,
+      the service may return 202 Accepted immediately and deliver chat/reasoning
+      results to this URL once processing is complete.
     properties:
       task:
         description: Optional task grounding this conversation.