Get Correct Content version on second pass events.

[KevinJump]

This is a little be of a sticking plaster on how the ContentService is updating it's version of the content as we progress (and save/publish it). We really need to return the new version of the item in the result of a couple of functions so it can make it back into the in memory array of items we then use in the second pass.

at the moment we are reloading the version if the second pass needs to then save it, in theory if something is trashed, with a schedule and not in the right order, that means we load it three times, but that is preferable to loading ever single content item on a second pass that we might not then need.

the longer term fix is to capture the new version at the place we save/publish it in the first pass, and then we won't have to reload things all the time. .

[Copilot]

Pull Request Overview

This PR ensures operations use the latest persisted version of content items during sync, reducing stale state issues between passes.

• Fetch and act on the latest item instance via GetByKey before mutating sort order, moving/restoring, and persisting schedules.
• Align second-pass save to a single-item API SaveItemAsync.
• Minor refactors to reduce redundant loads during second pass while keeping behavior consistent.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
uSync.Core/Serialization/Serializers/ContentSerializerBase.cs	Use latest item for sort order and trash/restore operations to avoid stale references.
uSync.Core/Serialization/Serializers/ContentSerializer.cs	Persist schedules on the latest item instance to reflect current version.
uSync.BackOffice/SyncHandlers/SyncHandlerRoot.cs	Switch to SaveItemAsync for second-pass persistence of a single changed item.

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