SoF: Fix runecrafting gold cost being non-translatable

Addresses #5889

data/campaigns/Sceptre_of_Fire/_main.cfg

@@ -110,6 +110,9 @@ Their tale I now relate...</i>
             name = "doofus-01"
         [/entry]
     [/about]
+    [lua]
+        code=<<wesnoth.dofile "campaigns/Sceptre_of_Fire/lua/rune-equip.lua">>
+    [/lua]
 [/campaign]
 
 #ifdef CAMPAIGN_SCEPTRE_FIRE

data/campaigns/Sceptre_of_Fire/lua/rune-equip.lua

@@ -0,0 +1,10 @@
+
+function wesnoth.wml_actions.rune_choice(cfg)
+   cfg = wml.literal(cfg)
+   for i, tag in ipairs(cfg) do
+        if tag[1] == "option" then
+            tag[2].label = tag[2].label:vformat{cost = tag[2].cost}
+        end
+    end
+    wesnoth.wml_actions.message(wml.tovconfig(cfg))
+end

data/campaigns/Sceptre_of_Fire/utils/rune-equip.cfg

@@ -2,7 +2,8 @@
 
 #define SOF_RUNIC_OPTION ID NAME DESC ICON COST EFFECT_WML
     image={ICON}
-    label= {NAME} + " <span style='italic'> ({COST}g)</span>"
+    cost={COST}
+    label= {NAME} + " <span style='italic'> (" + _"$cost|g" + ")</span>"
     description = {DESC}
     [command]
         [if]
@@ -280,7 +281,7 @@
             [filter]
                 find_in=rune_customer
             [/filter]
-            [message]
+            [rune_choice]
                 speaker=Thursagan
                 message= _ "I can hammer out a quick little runic charm, it should help you somewhat. This isn't the place to do really good work though, so the effects will vanish in the future. What do you say, is it worth a bit of gold and crystal?"
                 [option]
@@ -337,7 +338,7 @@
                         [/effect]
                     )}
                 [/option]
-            [/message]
+            [/rune_choice]
         [/event]
     [/event]