Fix non-functional 'Restart Game' button in save/load menu

[coderabbitai]

The 'Restart Game' button in the save/load menu (objects/obj_saveload/Draw_0.gml) was disabled due to crashes and needs to be repaired.

Background

The restart functionality was causing game crashes, so it was temporarily commented out in PR #846 with a TODO comment indicating it should be repaired.

Current State

• Code is commented out with the note: '//! Doesn't work properly, commented out until repaired;'
• The button UI and click handling logic exists but is disabled
• Users cannot restart games from the save/load menu

Expected Outcome

• Restart functionality should work without causing crashes
• Users should be able to restart games from the save/load menu safely

References

• PR: fix: Disable the "Restart" save button #846
• Comment: fix: Disable the "Restart" save button #846 (comment)
• Requested by: @EttyKitty