Fix: key the AI suggestion cache by model and endpoint (#13449)

---------

Co-authored-by: shamoon <4887959+shamoon@users.noreply.github.com>

src/documents/views.py

@@ -1530,10 +1530,15 @@ class DocumentViewSet(
             return HttpResponseBadRequest("AI is required for this feature")
 
         output_language = _get_llm_output_language(ai_config=ai_config, request=request)
-        llm_cache_backend = (
-            f"{ai_config.llm_backend}:{output_language}"
-            if output_language
-            else ai_config.llm_backend
+        llm_cache_backend = ":".join(
+            part
+            for part in (
+                ai_config.llm_backend,
+                ai_config.llm_model,
+                ai_config.llm_endpoint,
+                output_language,
+            )
+            if part
         )
 
         cached_llm_suggestions = get_llm_suggestion_cache(