- Replaced Azure and OpenAI provider calls with `postOpenAIStream` flow.
- Fixed stream error handling by retaining status, headers, and body on failures.
- Fixed stream parsing by handling raw JSON SSE frames and `[DONE]` events.
- Added `OpenAIHttpError` with parsed messages and timeout-aware retry behavior.
- Added remote-compaction tests for timeout, abort, and 500-fallback behavior.