GetItemCount via C_Item, reagents via C_Spell.GetSpellReagents

Drops the legacy pfUI.api.GetItemCount wrapper (name-based bag walk +
GetItemInfo per slot) entirely — both call sites switch to direct
C_Item.GetItemCount(itemID) calls.

actionbar reagent counter: drops the SPELL_REAGENTS tooltip-scan +
libtipscan dependency. UpdateSlot now does GetActionInfo(slot) →
spellID → C_Spell.GetSpellReagents → reagent itemID, stored per slot.
Counts update via C_Item.GetItemCount(itemID). reagent_counts is
keyed by itemID instead of localized name string. Multi-reagent
spells now resolve cleanly (only first reagent counted, matching old
single-name behavior). Macro and bag-item actions skip cleanly.

questitem: switches to hooksecurefunc("SetItemRef", ...) + the
modern GameTooltip:HasItem / :GetItem pair instead of monkey-patching
_G.SetItemRef and string.find-parsing the "item:NNN" out of the link.
Drops the libtooltip indirection for the regular tooltip path —
GameTooltip:GetItem returns name + itemID directly. AddTooltip
extended to accept the itemID (both callers already had it and were
discarding it).

api/api.lua

@@ -406,31 +406,6 @@ function pfUI.api.GetItemLinkByName(name)
   end
 end
 
--- [ GetItemCount ]
--- Returns information about how many of a given item the player has.
--- 'itemName'   [string]         name of the item
--- returns:     [int]            the number of the given item
-function pfUI.api.GetItemCount(itemName)
-  local count = 0
-  for bag = 4, 0, -1 do
-    for slot = 1, GetContainerNumSlots(bag) do
-      local _, itemCount = GetContainerItemInfo(bag, slot)
-      if itemCount then
-        local itemLink = GetContainerItemLink(bag,slot)
-        local _, _, itemParse = strfind(itemLink, "(%d+):")
-        local queryName = GetItemInfo(itemParse)
-        if queryName and queryName ~= "" then
-          if queryName == itemName then
-            count = count + itemCount
-          end
-        end
-      end
-    end
-  end
-
-  return count
-end
-
 -- [ FindItem ]
 -- Returns the bag and slot position of an item based on the name.
 -- 'item'       [string]         name of the item