[Feat] (MG_State, MG_Util, MG_Impl/GLImpl, MG_Backend/DirectGLES): desktop-GL single-channel client formats GL_GREEN/GL_BLUE/GL_ALPHA and _INTEGER variants - validate and readback via wide-RGBA channel extraction (GL CTS packed_pixels rgba8_format_green/blue read with them), unpack GREEN/BLUE(_INTEGER) TexImage uploads into the named channel with 0/1 defaults per table 3.3; GL_ALPHA keeps the legacy Red upload mapping (R8 storage + 000R swizzle), its readback corrected at the backend to source channel 3

MobileGL/MG_State/GLState/TextureState/TextureEnum.h

@@ -76,6 +76,14 @@ namespace MobileGL {
         BGRInteger,
         RGBAInteger,
         BGRAInteger,
+        // Desktop-GL single-channel client formats (table 3.3): the data holds one component that
+        // feeds the G, B or A channel; the remaining channels default to 0 (color) / 1 (alpha).
+        Green,
+        Blue,
+        Alpha,
+        GreenInteger,
+        BlueInteger,
+        AlphaInteger,
         StencilIndex,
         DepthComponent,
         DepthStencil,