feigndeath: use UnitIsFeignDeath + GetUnitField, drop tooltip cache

ClassicAPI's UnitIsFeignDeath reads UNIT_FIELD_FLAGS bit 29 directly —
the authoritative server flag, no detection guesswork needed. Combined
with Nampower's GetUnitField("health"), we read live HP off the
descriptor instead of caching the moment-of-death healthbar value via
libtipscan.

Drops the name-keyed cache, the UNIT_HEALTH / PLAYER_TARGET_CHANGED
event handlers, and the tooltip scanner. Also fixes the staleness bug
where a feigning hunter taking further damage kept showing the cached
snapshot from when feign first triggered — live read updates with
every UnitHealth call now.

modules/feigndeath.lua

@@ -1,29 +1,10 @@
 pfUI:RegisterModule("feigndeath", function ()
-  local cache = { }
-  local scanner = libtipscan:GetScanner("feigndeath")
-  local healthbar = scanner:GetChildren()
-
-  local cache_update = CreateFrame("Frame")
-  cache_update:RegisterEvent("UNIT_HEALTH")
-  cache_update:RegisterEvent("PLAYER_TARGET_CHANGED")
-  cache_update:SetScript("OnEvent", function()
-    if event == "PLAYER_TARGET_CHANGED" and UnitIsDead("target") then
-      scanner:SetUnit("target")
-      cache[UnitName("target")] = healthbar:GetValue()
-    elseif event == "UNIT_HEALTH" and UnitIsDead(arg1) and UnitName(arg1) then
-      scanner:SetUnit(arg1)
-      cache[UnitName(arg1)] = healthbar:GetValue()
-    elseif event == "UNIT_HEALTH" and UnitName(arg1) then
-      cache[UnitName(arg1)] = nil
-    end
-  end)
-
   local oldUnitHealth = UnitHealth
-  function UnitHealth(arg)
-    if UnitIsDead(arg) and cache[UnitName(arg)] then
-      return cache[UnitName(arg)]
-    else
-      return oldUnitHealth(arg)
+  function UnitHealth(unit)
+    if UnitIsFeignDeath(unit) then
+      local hp = GetUnitField(unit, "health")
+      if hp and hp > 0 then return hp end
     end
+    return oldUnitHealth(unit)
   end
 end)