'Proportional' encumbrance is not proportional

[RenechCDDA]

Following up on #163 (comment) ....

Here's two items from HHG, both say they have 10 encumbrance. armor_acidchitin copies from armor_chitin with a proportional encumbrance of 1.5 (50% more), but HHG doesn't recognize that.

https://cdda-guide.nornagon.net/item/armor_chitin

https://cdda-guide.nornagon.net/item/armor_acidchitin

And ingame:

[nornagon]

hm, it looks like currently in the data, armor_acidchitin doesn't have a proportional encumbrance specified: https://github.com/CleverRaven/Cataclysm-DDA/blob/cdda-experimental-2024-09-22-0113/data/json/items/armor/suits_protection.json#L78-L89

but i can definitely believe the Guide doesn't interpret this correctly!

[nornagon]

boots_western has proportional encumbrance of 2 over boots:

https://github.com/CleverRaven/Cataclysm-DDA/blob/03763473c2ae6d4e559306c74099890d306a8211/data/json/items/armor/boots.json#L991

but they display the same encumbrance in the Guide, so that'll be easier to test this bug.