Beaker panel TGUI / At least makes it functional (#93398)

## About The Pull Request

Makes Beaker Panel a TGUI so it actually works

<img width="787" height="295" alt="image"
src="https://github.com/user-attachments/assets/343056d2-f059-473d-a1eb-5604d2c3a38e"
/>

There's a lot more I want to do to this UI, namely UX and more features
(like changing grenade types) but I figured I should PR it now that it's
bare minimum functional so I don't get eaten by scope creep

Fixes #89954

## Changelog

🆑 Melbert
admin: Spawn-reagent-container works again, and it's a TGUI
/🆑

code/modules/admin/topic.dm

@@ -1272,9 +1272,6 @@
 		var/ban_id = href_list["unbanlog"]
 		ban_log(ban_id)
 
-	else if(href_list["beakerpanel"])
-		beaker_panel_act(href_list)
-
 	else if(href_list["reloadpolls"])
 		GLOB.polls.Cut()
 		GLOB.poll_options.Cut()