AI Catalog updates for governance and operations

What this post added

Introduced event-driven triggers for GitLab Duo Flows, enabling automated execution based on real GitLab events like merge request conflicts, draft-to-ready transitions, approvals, and work item creation. Added pipeline event filters for specific states (failure, success, cancellation). Implemented governance controls: 'Disable custom agents and flows' and 'Restrict the AI catalog to your group hierarchy'. Enhanced flow configuration validation to catch errors before saving. Launched a public beta for an AI model allowlist and default model configuration.