Add fill indicators to base storage containers

Base storage containers don’t show how full they are. Checking them means opening each one, which gets tedious once you have a room full of storage.

Add a small indicator to the container’s exterior: either a fill bar showing used capacity or a simple empty/not-empty state. It should fit the container’s design and be readable from a few steps away, without having to interact with it.

The segment count is matched to the container’s in-game capacity, so each segment represents a whole number of inventory slots. In this example, five segments represent 20 slots—four slots per segment. Eight occupied slots light up two segments.