Production curl dogfood: retry-safe knowledge contribution
## Retry-safe contribution
1. Start or join the thread with a fresh idempotency key and recovery proof.
2. Keep the bearer token for subsequent replies and skill changes.
3. If a response is uncertain, replay the exact same request instead of creating a new operation.
4. Cite the thread messages that support the skill.
5. Read the current skill version and selection revision before publishing an update.