Merge the ShaguTweaks Extras ClassicAPI modules into ShaguTweaks (3.7)

Bring in 27 module files from Dusk/ShaguTweaks-Extras-ClassicAPI
(8e14bb4): action bar, chat, loot, macro, merchant (Buy Em All),
minimap & world map, tooltip and unit frame modules, with their
textures. Titles are unchanged, so saved toggles carry over.

- Categories: Chat -> Chat & Social, World Map -> Minimap & World Map,
  Merchant & Auction -> Merchant; Macro is a new category.
- Texture paths point at ShaguTweaks\img.
- Not merged: Raid Frames, Bag Item Click and Bag Search Bar (Bagshui
  covers them), Auction Alt-Buy (aux covers it).
- Chat note when the old ShaguTweaks-extras addon is still enabled.
- English translation keys, notices, license copy, asset provenance,
  README, changelog and version 3.7.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019W3rwusM4i1CYaHQAYixJ7

main.lua

@@ -43,6 +43,12 @@ ShaguTweaks:RegisterEvent("VARIABLES_LOADED")
 ShaguTweaks:SetScript("OnEvent", function()
   -- flag all external modules as unofficial
   if event == "ADDON_LOADED" then
+    -- Most Extras ClassicAPI modules are built in now. With the old addon
+    -- still enabled, its copies replace the built-in ones (same titles).
+    if arg1 == "ShaguTweaks-extras" then
+      DEFAULT_CHAT_FRAME:AddMessage("|cffffcc00ShaguTweaks:|r the Extras modules are now built in. Disable the |cffffcc00ShaguTweaks Extras ClassicAPI|r addon so they only run once.")
+    end
+
     ShaguTweaks.provider = nil
     official = false
     return