Commit cc2b56b2 changed the tool_progress_callback signature from
(name, preview, args) to (event_type, name, preview, args, **kwargs)
but the API server's chat completion streaming callback was not updated.
This caused tool calls to not display in Open WebUI because the
callback received arguments in wrong positions.
- Update _on_tool_progress to use new 4-arg signature
- Add event_type filter to only show tool.started events
- Add **kwargs for optional duration/is_error parameters
7ec838507a