npc buy fuel and ammo until there is nothing or almost nothing left

NPC purchasing has been paused until I can investigate further.

This has been fixed. Sales logs for NPCs weren't working properly, every sale was logging as 1 item sold but with the full value of the sale. Only the sales logs were affected.

NPC purchasing has also been improved so they should only buy things when they need them - particularly military goods only when they're fighting.