luau/UniversalSynSaveInstance — reverse-engineered prompt

Build me a Roblox Luau utility that brings back a reliable saveinstance style function for my own projects and permitted debugging work. I want to be able to load one function, pass in an Options table, and have it save the current place or a chosen object or model to Roblox XML files, including rbxmx for models.

It should handle common options like file path, extra instances, nil instances, player saving, removing player characters, ignoring defaults, decompiling scripts with timeout and ignore lists, status messages, callbacks, and a safe mode for better compatibility. Please make it stable and avoid changing the running game while it saves.

Include a simple loadstring example and clear docs for each option. Keep the required UniversalSynSaveInstance credit and license text in the output. Don’t add binary rbxl or rbxm unless it’s straightforward, just leave a clear TODO. Look up the current Roblox file format docs online if you need to.