pfSellData: drop sell column, use C_Item.GetItemSellPriceByID

Each pfSellData entry was a "sell,buy" string. The sell price duplicates
what C_Item.GetItemSellPriceByID returns from the engine's item DBC, so
it's redundant in our table — only the buy price (curated from real
vendor encounters, not a static item property) needs to live here.

Transformed every [id]="X,Y" entry across env/tables.lua, compat/tbc.lua,
and modules/turtle-wow.lua to [id]=Y via sed. Format is now itemid →
buyPrice (number, copper).

sellvalue.lua: reads sell from C_Item.GetItemSellPriceByID(id), reads
buy from pfSellData[id]. Items that have only a sell price (not in
pfSellData) now display sell-only — previously they got no tooltip
addition because the lookup gated on table membership. Items with
buy-only (sell == 0 in old data) still display buy correctly.

autovendor.lua: replaces the pfSellData[id] gate (which only checked
table membership and unused the parsed sell/buy) with a direct
C_Item.GetItemSellPriceByID > 0 check — the engine's canonical
"is this item sellable to a vendor" answer.

modules/autovendor.lua

@@ -58,10 +58,9 @@ pfUI:RegisterModule("autovendor", "vanilla:tbc", function ()
       return
     end
 
-    -- get value
+    -- only proceed for items the engine reports as vendor-sellable
     local id = C_Container.GetContainerItemID(bag, slot)
-    if pfSellData[id] then
-      local _, _, sell, buy = strfind(pfSellData[id], "(.*),(.*)")
+    if (id and C_Item.GetItemSellPriceByID(id) or 0) > 0 then
       this.count = this.count + 1
     end