Remove redundant headless virtual size stub

Drop the stale Radius Jewel Finder stub after rebasing onto origin/dev, where HeadlessWrapper already gets virtual screen sizing from the shared headless path.

Reviewed in 20260523T092557Z-codex-0f35438f3607.

Author: mcagnion

src/HeadlessWrapper.lua

@@ -48,9 +48,6 @@ function RenderInit(flag, ...) end
 function GetScreenSize()
 	return 1920, 1080
 end
-function GetVirtualScreenSize()
-	return 1920, 1080
-end
 function GetScreenScale()
 	return 1
 end