eqcompare: rewrite on top of ClassicAPI SetHyperlinkCompareItem

Drop the manual C_Item.GetItemStatDelta rendering (inline annotations
and bottom-block summary) in favor of driving native shopping tooltips
via SetHyperlinkCompareItem — the 3.3.5 flow now available through
ClassicAPI. Way less code, and Blizzard's own comparison rendering
handles all stat types uniformly.

Also revert the mode dropdown back to a single basestats checkbox — the
new implementation doesn't distinguish base vs extended (Blizzard's
tooltip shows everything the item exposes), so the two-level control
was redundant. Existing basestats configs pass through unchanged.

AtlasLootTooltip now goes through the shared HookTooltip helper instead
of a bespoke OnShow shim.

api/config.lua

@@ -751,7 +751,7 @@ function pfUI:LoadConfig()
   pfUI:UpdateConfig("tooltip",    nil,           "movespeed",        "0")
   pfUI:UpdateConfig("tooltip",    nil,           "alpha",            "0.8")
   pfUI:UpdateConfig("tooltip",    nil,           "alwaysperc",       "0")
-  pfUI:UpdateConfig("tooltip",    "compare",     "mode",             "extended")
+  pfUI:UpdateConfig("tooltip",    "compare",     "basestats",        "1")
   pfUI:UpdateConfig("tooltip",    "compare",     "showalways",       "0")
   pfUI:UpdateConfig("tooltip",    "vendor",      "showalways",       "1")
   pfUI:UpdateConfig("tooltip",    "questitem",   "showquest",        "1")
@@ -1372,22 +1372,6 @@ function pfUI:MigrateConfig()
     end
   end
 
-  -- migrate tooltip.compare.basestats + extendedstats into a single mode dropdown
-  if pfUI_config.tooltip and pfUI_config.tooltip.compare then
-    local cmp = pfUI_config.tooltip.compare
-    if cmp.basestats or cmp.extendedstats then
-      if cmp.basestats == "0" then
-        cmp.mode = "off"
-      elseif cmp.extendedstats == "0" then
-        cmp.mode = "base"
-      else
-        cmp.mode = "extended"
-      end
-      cmp.basestats = nil
-      cmp.extendedstats = nil
-    end
-  end
-
   -- Remove "Show only own debuffs" from unitframes and nameplates
   -- (feature was removed; only Target Debuff Bar in buffwatch keeps it)
   if pfUI_config.nameplates then