MGS Origins Expanded 3.7.4 — Runtime Hotfix

Fix targeted by this build:
- Removed all direct Level.isClientSide field references from the MGS runtime classes.
- The previous 3.7.3 build crashed during chunk/entity promotion with NoSuchFieldError / NoSuchMethodError for Level.isClientSide.
- Both MGSEngine and MGSVisualEngine were patched.
- No projectile-spawn handler-side check now resolves Level.isClientSide.

Compatibility target: Minecraft 1.20.1 / Forge 47.4.x
Validated statically: no bytecode reference to Level.isClientSide remains in the two MGS runtime classes.
