Accessory checkin via API reported wrong target user

[uberbrady]

This is a cherry-pick of the same commit that was merged to master - so sorry for the mis-target!

[what-the-diff]

PR Summary

• Modification of Check-in Method in Accessories Controller
  The way we record the check-in action has been updated for better data accuracy. We previously logged the action using the user ID from the 'accessory_user' model. Now, we're using the 'assigned_to' property from the same model. This change ensures we log the right user who performed the check-in action.

[snipe]

Thanks!