Normalize the readable reasoning providers already return into a
canonical `ReasoningOutput` and carry it through the `agent.message`
run event to storage, SSE, and JSONL.
The shape is derived from the final response's canonical message
content rather than stored a second time, so there is no duplicate
source of truth and retried or replaced streaming buffers never
become durable reasoning. OpenAI-compatible `reasoning_details` are
now preserved verbatim as an opaque content part; only known readable
members are normalized out of them, leaving encrypted entries for a
later provider-aware replay phase.
This phase is passive: no request parameters change, no capability
guessing, and no newly observed provider field is replayed.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
