- Add sequence_number to ALL streaming events (created, in_progress,
output_item.added, content_part.added, all delta events)
- Add output_index to all events referencing output items
- Add content_index to content-related events
- Populate full response object in response.created and
response.in_progress events (was only {id, object, status})
- Add id field to function_call output_item.added events
- Add status: completed to reasoning output_item.done events
- Counter state persisted across streaming chunks via task_result_state
Fixes: spec-compliant client libraries (async-openai) that require
these fields can now parse all streaming events without error.
Refs: ggml-org/llama.cpp#21174 (fumlig review comment)