## Summary
Changed history reconciliation to use `promptId` instead of `queueIndex`
to support cloud environments that don't have queue indices.
Refactored into pure functions with expressive naming.
## Changes
- Use `promptId` (unique UUID) for reconciliation instead of
`queueIndex` (not available in cloud)
- Extract `reconcileHistoryWithServer` with helpers: `extractPromptIds`,
`isAddedAfter`, `sortNewestFirst`
- Added 34 tests covering reconciliation edge cases, sorting, and limits
┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6327-use-prompt-id-rather-than-queue-index-for-history-reconciliation-2996d73d3650818e9471dbeb53cc23bb)
by [Unito](https://www.unito.io)
