User folders: save games and Settings.cfg in Documents\Sacred

The game's ANSI file API calls are hooked; paths under save\ and
Settings.cfg are redirected to Documents\Sacred\save and
Documents\Sacred\config, copied there once from the game folder.
The shared chest uses the same save folder.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/mods/sharedchest.h

@@ -2,7 +2,7 @@
 
 namespace mods::sharedchest {
 
-// Writes the shared chest (save\shared_chest.json); called after a hero is saved.
+// Writes the shared chest (shared_chest.json in the save folder); called after a hero is saved.
 void Save();
 
 } // namespace mods::sharedchest