Fix TMNT: Shredder's Revenge startup with macOS game data

[Producdevity]

Game Information

• Update Port for: TMNT: Shredder's Revenge
• URL: https://store.steampowered.com/app/1361510/Teenage_Mutant_Ninja_Turtles_Shredders_Revenge/

Game data copied from macOS can contain .DS_Store files. TMNT's FNA content loader treats these files as assets and attempts to load Content/AssetPacks/.xnb, causing startup to fail.

This removes .DS_Store files from gamedata before launch, similar to what the Celeste launch script does for ._* metadata.

Testing

• Tested on ROCKNIX. removing .DS_Store cleared ContentLoadException: Could not load asset AssetPacks/! and reached the splash screens.
• bash -n ports/tmntsr/TMNTShreddersRevenge.sh

Authorship & Testing

• I wrote and understand this script/patch myself, or clearly marked which parts came from an AI assistant and reviewed them
• I can explain every non-standard line in my launch script