CI: End-to-end tests for async

Is your feature request related to a problem?
We currently lack end-to-end CI tests for the async pipeline, which leads to unnoticed regressions impacting customers. Without monitoring and alerting, issues may persist before they are detected.

Describe the solution you'd like

• Add end-to-end CI tests for the async pipeline using a dedicated test account.
• Run tests every 5 minutes on /llm/call, /llm/chain, and collection/document flows.
• Verify job completion within SLA, validate responses, and ensure correct callback delivery.
• Implement alerts for failures or latency breaches.
• Track success rate, latency, and callback delivery in dashboards.
• Run these tests on every PR and block merges if they fail.

Commencez par retracer le pipeline asynchrone derrière /llm/call, /llm/chain et les flux de collections/documents, puis examinez la configuration CI existante et les points d’entrée des tests. Le travail est considéré comme terminé lorsque des vérifications end-to-end planifiées et par PR vérifient le respect du SLA, les réponses et les callbacks, avec des alertes en cas d’échec ou de latence, ainsi que des tableaux de bord pour le taux de réussite, la latence et la livraison des callbacks.