tip leaf: terminate WS streams on error events (#50854)

[kvnloo]

Goal

Fork-only tip leaf for origin anomalyco#50854 — terminate OpenAI Responses websocket streams on top-level error events.

Context

Origin tip SHA 583811a7b456790262501f510d1e9d72194071cc. Base: fork dev. github_writes_origin=0. Codex promote parked.

Acceptance

• CLEAN fail→pass on tip test terminates an OpenAI Responses stream on a top-level error event
• GREEN 1 / NEG 1 fail / RESTORE 1

Return

Ship fork PR with grok bot + envelope; no origin writes.