Prevent/warn about loading old saves

One issue we get is that users load saves from the unmodded game, which don't work on the modded game.

If there is some way to differentiate between modded and unmodded saves, we could show a warning before the user loads the save that the save won't work properly.

Even if the save has no identifying information, if the save's date modified is older than the mod's install version tracking file's creation date (installedVersionData.json), then it's probably an old save.

We don't need to worry about the save file repeatedly having the warning pop-up, as users will either create a new save, or overwrite their old one, which should cause the date modified to become newer and no longer cause the warning (assuming their save loads correctly).

I realize that we have a warning in the installer about old saves, this issue still happens from time to time. Would be better to prevent it from happening altogether.

Look for save file loading logic, likely in a class handling game state or serialization. Check for existing version tracking via installedVersionData.json. Determine how to compare save file timestamps and inject a warning dialog. Testing involves loading both modded and unmodded saves to ensure the warning triggers appropriately.

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