use the chat spritesheet for byond member ooc icons (#96384)

## About The Pull Request

partial port of my fixups from
https://github.com/Monkestation/Monkestation2.0/pull/11644

this refactors the byond member icon in OOC use the chat spritesheet,
instead of `icon2html`.
<img width="772" height="387" alt="2026-06-06 (1780794864) ~
dreamseeker"
src="https://github.com/user-attachments/assets/9e4c0e3e-280f-4fda-b0ee-c78b8aa33e76"
/>

also as a result, this makes the byond member icon align better with the
text and be slightly less crunchy.
here's how it was before, for reference:
<img width="293" height="32" alt="image"
src="https://github.com/user-attachments/assets/15c8a78d-7752-4c07-a2d4-b4ceebc7f362"
/>

## Why It's Good For The Game

why did this use icon2html that's dumb. better performance i guess. and
looks better on the eyes.

## Changelog
🆑
fix: Made the BYOND member OOC icon better aligned to the text.
/🆑

code/modules/asset_cache/assets/chat.dm

@@ -11,3 +11,7 @@
 		if (icon != 'icons/ui/chat/language.dmi')
 			var/icon_state = initial(L.icon_state)
 			insert_icon("language-[icon_state]", uni_icon(icon, icon_state))
+
+	var/datum/universal_icon/byond_member = uni_icon('icons/ui/chat/member_content.dmi', "blag")
+	byond_member.scale(16, 16)
+	insert_icon("byond_member", byond_member)