Add Loot History module

A pfUI-native group-loot roll history window built on ClassicAPI's
C_LootHistory backport, adapted from the anniversary Blizzard reference.

- Movable/scrollable window (ESC-closable, Clear button) listing rolled
  items; each row expands to per-player rolls.
- Item icon/name/quality rendered via the !!!ClassicAPI Item mixin
  (Item:CreateFromItemLink + ContinueOnItemLoad), so uncached items load
  asynchronously and repaint their row.
- Winner shown on the collapsed row (name/roll/roll-type) and marked in the
  expanded list with a checkmark left of the name (matches the reference).
- Expansion state keys on the stable rollID; events (FULL_UPDATE /
  ROLL_CHANGED / ROLL_COMPLETE) drive a rebuild while shown, and re-attach
  the scroll child so a growing list scrolls without a /reload.
- Toggle via /loothistory or /lh; optional auto-show on new rolls behind
  loothistory.autoshow (default off).

api/config.lua

@@ -196,6 +196,8 @@ function pfUI:LoadConfig()
   pfUI:UpdateConfig("loot",       nil,           "rollannounce",     "0")
   pfUI:UpdateConfig("loot",       nil,           "raritytimer",      "1")
 
+  pfUI:UpdateConfig("loothistory", nil,          "autoshow",         "0")
+
   pfUI:UpdateConfig("unitframes", nil,           "disable",          "0")
   pfUI:UpdateConfig("unitframes", nil,           "pastel",           "1")
   pfUI:UpdateConfig("unitframes", nil,           "custom",           "0")