Add API_Check.lua as the first TOC entry. When the ClassicAPI DLL is
absent or below the minimum version it sets pfUI_disabled and stands up
an inert stub so the rest of the addon no-ops instead of flooding load
errors: modules and skins register their bodies into no-ops, and the
setfenv'd api/lib files run inside an environment where CreateFrame and
any missing global resolve to a null object -- so no real frames or live
handlers are created and missing API calls just return null. pfUI.lua
bails early on pfUI_disabled.
