Add stream_options: { include_usage: true } to iFlow streaming requests
to get token usage data in the final streaming chunk. This fixes token
counts showing as 0 for iFlow streaming requests.
Only injected when streaming is enabled and body.messages exists (OpenAI
format), and the client hasn't already set stream_options.
Note: Applied only to iFlow executor instead of BaseExecutor to avoid
affecting all providers globally. This gives us more control and allows
testing with iFlow first.
Fixes#74
Co-authored-by: Ibrahim Ryan <ryan@nuevanext.com>
Made-with: Cursor
