Fix third UnboundLocalError for 'time' variable in copy_live_system method

- Removed local import of 'time' module in copy_live_system method
- This was the third instance of the same variable shadowing issue
- Local import was creating a variable that shadowed the globally imported module
- This caused UnboundLocalError when trying to access time.sleep(0.01) during system copy
- Now uses the globally imported time module correctly
- System copy process should now complete without variable scoping errors

This completely resolves all UnboundLocalError issues in the AutoInstaller GUI
by ensuring no local imports shadow the globally imported time module anywhere in the code.

autoinstaller_gui/autoinstallergui.py

@@ -790,7 +790,6 @@ class InstallerWorker(QThread):
                     last_update_time = current_time
 
                 # Allow GUI event processing by yielding control
-                import time
                 time.sleep(0.01)
 
             # Check return code