GetChildChatsByParentIDs sorted created_at ASC, but the cache
helper appended new children to the end. On refetch the API and
cache agreed on oldest-first, putting the just-created child at
the bottom. Users expect newest first, matching the root-chat
sidebar convention.
- SQL: change child sort to created_at DESC, id DESC.
- Cache: prepend instead of append in addChildToParentInCache
(renamed from appendChildToParentInCache to avoid leaking
position semantics).
- Test: update ordering assertion to expect newest-first.
Refs #24404
Mathias Fredriksson
467430d8fa