Add StarMapAfterSave and StarMapAfterLoad hooks

[LaurensDeV]

The problem

A mod that keeps per-save state has no way to be told when a save happens. There is no save or load hook, and neither Universe, Program nor GameSaves raises an event, so the only signal available is polling the timestamp of universe.xml.

Polling leaves a window. Save and load inside it and the mod writes nothing for that save, and then — when the poll finally fires and sees the stamp change — writes the freshly-defaulted state over the file. Shortening the interval narrows the window without closing it, and costs a file stat every frame to do so.

I hit this in a mod that stores per-craft settings inside the save folder, which is where they belong: deleting a save deletes them, copying copies them, renaming takes them along.

The change

Two attributes, following the existing ones:

[StarMapAfterSave]
public void OnSaved(DirectoryInfo saveDirectory);

[StarMapAfterLoad]
public void OnLoaded(DirectoryInfo saveDirectory);

Both pass the save's directory, because a save is a directory and what a mod usually wants is to put a file beside universe.xml.

Patched on UniverseData.WriteTo(DirectoryInfo) and UniverseData.LoadFrom, both public. WriteTo is overloaded, so the patch names the argument type.

What I could not verify

The repository pins RocketWerkz.KSA.Ref 2026.7.6.4939, which is not on nuget.org, so I could not restore it. I compiled StarMap.API cleanly and type-checked StarMap.Core against KSA 2026.8.5.5168 from a local install — with that build, the pre-existing ConfirmRestart* files do not compile (PopupButton/IPopupWidget and DrawUi have moved), which is unrelated to this change but did stop a full solution build here.

So: the method shapes are worth a second look against the pinned build, and this is a draft rather than ready to merge for that reason. If WriteTo/LoadFrom differ in 2026.7.6.4939, the patch targets need adjusting.