fix(cloud-task): attribute ai_generation task_user_id to task creator

[tatoalo]

Problem

Cloud task runs mis-attribute their LLM analytics. Every $ai_generation event emitted during a cloud run is stamped with task_user_id: 0 instead of the id of the user who created the task, so per-user attribution/cost for cloud runs is wrong

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit 7fd2ac0.}

[github-actions]

Trivial one-liner fallback fix with no security implications or API contract changes.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "fix(cloud-task): attribute ai_generation..." | Re-trigger Greptile}