Armor Type Warning (Cloth / Leather / Mail / Plate)

* No unnecessary tooltip:Show() calls; instead, it uses the official built-in tooltip update system.
* Uses GetItemInfoInstant() to efficiently check item data without causing tooltip spam.
* Uses TooltipDataProcessor.AddTooltipPostCall(Enum.TooltipDataType.Item) for modern Retail compatibility.
* Uses the official in-game color handling with RED_FONT_COLOR:WrapTextInColorCode instead of hardcoded hex colors, so it automatically adapts and blends into the UI seamlessly.

* No flickering or disappearing lines, even when tooltips are dynamically rebuilt.
* Only checks tooltips that are visible, avoiding unnecessary background processing and Lua errors.

* Checks if the tooltip already has the warning line.
* Ensures the warning is never added twice, keeping the tooltips clean.