Fixes the universal scanner's sprites and adds contextual screentips. (#70926)

## About The Pull Request

This PR fixes a minor icon_state name discrepancy when switching to the
sales tagger mode (I forgot to add a space to the icon_state, which
carried over to the radial).

I then read #70909 which brings up several issues with the item, and
after actually testing it, everything works as intended. The issue it
appears is that it's not clear enough that the functionality is the same
as it was previously on the prior items, so we've added contextual
screentips to all 3 modes of the scanner.


![image](https://user-images.githubusercontent.com/41715314/198892524-65845906-736c-4859-87b2-304278b0c7a6.png)

## Why It's Good For The Game

Fixes #70909. Improves player feedback on the three modes of the
universal scanner through context.

## Changelog

🆑
fix: The universal scanner now properly show all three options in the
radial with sprites, due to a missing space.
qol: The universal scanner now has contextual screentips within all
three of its modes.
/🆑

Co-authored-by: Mothblocks <35135081+Mothblocks@users.noreply.github.com>

code/modules/cargo/universal_scanner.dm

@@ -38,10 +38,11 @@
 		"price tagger" = image(icon = src.icon, icon_state = "price tagger"),
 		"sales tagger" = image(icon = src.icon, icon_state = "sales tagger"),
 ))
+	register_context()
 
 /obj/item/universal_scanner/attack_self(mob/user, modifiers)
 	. = ..()
-	var/choice = show_radial_menu(user, src , scale_mode, custom_check = CALLBACK(src, .proc/check_menu, user), radius = 36, require_near = TRUE)
+	var/choice = show_radial_menu(user, src, scale_mode, custom_check = CALLBACK(src, .proc/check_menu, user), radius = 36, require_near = TRUE)
 	if(!choice)
 		return FALSE
 	if(icon_state == "[choice]")
@@ -117,7 +118,7 @@
 		if(!chosen_price || QDELETED(user) || QDELETED(src) || !user.canUseTopic(src, be_close = TRUE, no_dexterity = FALSE, no_tk = TRUE) || loc != user)
 			return
 		new_custom_price = chosen_price
-		to_chat(user, span_notice("The [src] will now give things a [new_custom_price] cr tag."))
+		to_chat(user, span_notice("[src] will now give things a [new_custom_price] cr tag."))
 
 /obj/item/universal_scanner/CtrlClick(mob/user)
 	. = ..()
@@ -145,8 +146,21 @@
 			. += span_notice("<b>Ctrl-click</b> to clear the registered account.")
 
 	if(scanning_mode == SCAN_PRICE_TAG)
-		. += span_notice("The current custom price is set to [new_custom_price] cr.")
+		. += span_notice("The current custom price is set to [new_custom_price] cr. <b>Right-click</b> to change.")
 
+/obj/item/universal_scanner/add_context(atom/source, list/context, obj/item/held_item, mob/user)
+	switch(scanning_mode)
+		if(SCAN_SALES_TAG)
+			context[SCREENTIP_CONTEXT_LMB] = "Tag package"
+			context[SCREENTIP_CONTEXT_ALT_LMB] = "Change price"
+			context[SCREENTIP_CONTEXT_CTRL_LMB] = "Clear target account"
+			context[SCREENTIP_CONTEXT_ALT_LMB] = "Change payout %"
+		if(SCAN_PRICE_TAG)
+			context[SCREENTIP_CONTEXT_LMB] = "Price item"
+			context[SCREENTIP_CONTEXT_RMB] = "Set price"
+		if(SCAN_EXPORTS)
+			context[SCREENTIP_CONTEXT_LMB] = "Scan for export value"
+	return CONTEXTUAL_SCREENTIP_SET
 /**
  * Scans an object, target, and provides it's export value based on selling to the cargo shuttle, to mob/user.
  */