[Producer] Upstream Bug – Intermittent streaming disconnects and retry behavior

[github-actions]

Context

Mirrors upstream bug: openai#1581

Streaming intermittently disconnects with: "stream disconnected before completion: stream closed before response.complete; retrying…".

Scope

Potentially related to but broader than openai#1481. Affects general streaming stability and retry behavior mid-conversation.

Acceptance Criteria

• Add diagnostics around stream lifecycle and retries
• Stabilize streaming with bounded retries, jitter, and clear user messages
• Ensure idempotency and no duplicate tool executions on retry
• Include integration test simulating interrupted streams

Refs: #6, upstream: openai#1581; related: the mirrored issue for openai#1481