Adds an engineering cart (#21110)

## About PR

Sprites are ported from Paradise Station, made by McRamon.

This cart is capable of holding the following:

- 2x sheet stacks of each steel, glass and plasteel.
- mechanical, electrical and emergency toolboxes, one each.
- light replacer

The one that spawns in engineering begins with all 3 toolboxes.
This cart costs 15 plasteel to craft, 100 credits to order from cargo.
Removes relevant toolboxes this cart spawns with in the department.

## Images

<img width="605" height="486" alt="Screenshot_4"
src="https://github.com/user-attachments/assets/59487676-bc5e-4f42-8c8e-d5d59add8481"
/>


https://github.com/user-attachments/assets/88e596ed-06e3-4047-89a8-452d1b13f466



### Asset Licenses
The following assets that **have not** been created by myself are
included in this PR:

| Path | Original Author | License |
| --- | --- | --- |
| icons/obj/engicart.dmi | McRamon (Paradise Station) | CC BY-SA 3.0 |

code/modules/mob/mob_movement.dm

@@ -329,7 +329,7 @@
 
 		//Wheelchair pushing goes here for now.
 		//TODO: Fuck wheelchairs.
-		if(istype(mob.pulledby, /obj/structure/bed/stool/chair/office/wheelchair) || istype(mob.pulledby, /obj/structure/janitorialcart))
+		if(istype(mob.pulledby, /obj/structure/bed/stool/chair/office/wheelchair) || istype(mob.pulledby, /obj/structure/janitorialcart) || istype(mob.pulledby, /obj/structure/engineeringcart))
 			var/obj/structure/S = mob.pulledby
 			move_delay += S.slowdown
 			return mob.pulledby.relaymove(mob, direct)