tgui reagent guidebook & tgui updates (#6161)

Co-authored-by: silicons <no@you.cat>

code/controllers/subsystem/processing/chemistry.dm

@@ -17,8 +17,8 @@ PROCESSING_SUBSYSTEM_DEF(chemistry)
 
 // honestly hate that we have to do this but some things INITIALIZE_IMMEDIATE so uh fuck me I guess!
 /datum/controller/subsystem/processing/chemistry/PreInit(recovering)
-	initialize_chemical_reactions()
 	initialize_chemical_reagents()
+	initialize_chemical_reactions()
 	return ..()
 
 /**

code/controllers/subsystem/tgui.dm

@@ -360,6 +360,7 @@ SUBSYSTEM_DEF(tgui)
 		// Inform the UIs of their new owner.
 		ui.user = target
 		target.tgui_open_uis.Add(ui)
+		source.on_ui_transfer(source, target, ui)
 	// Clear the old list.
 	source.tgui_open_uis.Cut()
 	return TRUE