[Bug]: loadout_addItems may not add any primary magazines

[jaj22]

The loadout_addItems function seems to have a bug that can cause primary magazines to go missing. I think it's because it always adds all items in a batch (eg. all five primary magazines) to the first container that fits, or the backpack (potentially overloaded) as a fallback. There's logic for trimming the batches, but this only applies if the total free space is insufficient. So the failure case would be this:

• Batch of magazines would fit in uniform + vest total load.
• Batch of magazines doesn't fit in either uniform or vest.
• The unit has no backpack.

Easiest fix is probably to add a check for the no-backpack case and dump the whole batch into the vest in that case.