Fix CI PR 4902

Goal

Get the current PR back to green by fixing the active CI failure instead of guessing at old logs.

Checklist

• [in_progress] Fetch the current failing CI checks and local learnings
• [pending] Reproduce the failure locally
• [pending] Implement the minimal fix
• [pending] Run targeted verification and the full PR gate
• [pending] Update the PR branch

Notes

• User asked to "fix ci" without a specific failure, so the live PR checks are the source of truth.
• Current failing run is CI for commit 1a7eeb74a.
• The failure is pnpm check -> pnpm test:slowest, not lint, build, or typecheck.
• GitHub runner flagged four AI chat specs over the fast-suite per-test threshold:
  • packages/ai/src/react/ai-chat/hooks/useAIChatEditor.spec.tsx
  • packages/ai/src/react/ai-chat/hooks/useEditorChat.spec.tsx
  • packages/ai/src/react/ai-chat/utils/getLastAssistantMessage.spec.ts
  • packages/ai/src/react/ai-chat/utils/submitAIChat.spec.ts
• The CI log explicitly says to move those specs to *.slow.ts[x].