Add RoomAiUpdated, RepoCreated, RepoUpdated, RepoDeleted event types.
Publish RoomAiUpdated after room_ai upsert/delete and repo events
after repo create/update. Always set model_name in AI list response
(fallback to "AI {uuid}" when model lookup fails) so frontend never
displays a raw UUID.
- Add #[serde(default)] to MergeAnalysisQuery.their_oid and MergeRefAnalysisQuery fields
since they come from path parameters, not query strings
- git_readme/git_commit_count/git_contributors: default to repo.default_branch
instead of HEAD to avoid errors when HEAD points to refs/heads/master but
the actual default branch is main