PHLEGM v8 Revision r87 - ARGB32 GUI icon pipeline

Windows icon browser:
- CHOP baked 0xAARRGGBB frames are written directly into cached top-down
  32-bit DIBSections (premultiplied ARGB), preserving full alpha and RGB.
- AlphaBlend with AC_SRC_ALPHA composites onto the GUI background.
- Cache fallback uses the identical DIB/AlphaBlend path.
- Old GDI primitives remain only for unbaked / non-CHOP icon fallback.
- No monochrome masks, SetPixelV, color-key clipping, or opaque SRCCOPY
  in the baked CHOP icon paint path.

Linux icon browser:
- Cairo ARGB32 already existed; now cairo_set_source_rgba also respects
  the input alpha channel rather than converting all nonzero alpha to opaque.

CHOP geometry definitions retain binary occupancy for 3D shape construction.
Those occupancy masks do NOT define the pixel format of the GUI renderer.

Validation: tests/GUI-ARGB32-Pipeline.Tests.ps1 checks platform composition
boundaries. Perform a real Windows GUI build and confirm the metallic/silver
CHOP faces and black edges display correctly; native build/runtime was not
available in this environment.
