fix: pass chat_id to internal task calls for consistent function context (#20585)

Ensure chat_id is reliably passed to function pipelines/manifolds during internal task invocations (web search query generation, RAG query generation, image prompt generation).

This allows stateful functions to maintain per-chat state without fragmentation, as they will now receive a consistent chat_id for all chat-scoped invocations including internal tasks.

Backend changes:
- Pass chat_id in generate_queries call for web search
- Pass chat_id in generate_queries call for RAG/retrieval
- Pass chat_id in generate_image_prompt call

Frontend changes:
- Add optional chat_id parameter to generateQueries API function
- Add optional chat_id parameter to generateAutoCompletion API function

Fixes #20563

backend/open_webui/utils/middleware.py

@@ -1255,6 +1255,7 @@ async def chat_web_search_handler(
                 "messages": messages,
                 "prompt": user_message,
                 "type": "web_search",
+                "chat_id": extra_params.get("__chat_id__"),
             },
             user,
         )
@@ -1585,6 +1586,7 @@ async def chat_image_generation_handler(
                     {
                         "model": form_data["model"],
                         "messages": form_data["messages"],
+                        "chat_id": metadata.get("chat_id"),
                     },
                     user,
                 )
@@ -1691,6 +1693,7 @@ async def chat_completion_files_handler(
                         "model": body["model"],
                         "messages": body["messages"],
                         "type": "retrieval",
+                        "chat_id": body.get("metadata", {}).get("chat_id"),
                     },
                     user,
                 )