Add the optional Forward+ desktop HQ build

Package a Forward+ preset with volumetric fog, SDFGI and a volumetric flashlight
for a separate Linux/Windows Desktop HQ zip. Gate the effects on a real
RenderingDevice, tune LATE fog, and adapt local light falloff for Godot 4.7.
Record the Compatibility/Forward+ A/B captures and metrics, add the artifact to
the build/publish scripts, and keep the default Compatibility/Web path
unchanged. Headless 231/231, Python 87/87; exported HQ binary boots with Vulkan.

tools/publish_release.sh

@@ -67,6 +67,7 @@ extras=(
   "build/gig-line-setup-$VERSION.exe"
   "build/gig-line-$VERSION-x86_64.AppImage"
   "build/gig-line-web-$VERSION.zip"
+  "build/gig-line-desktop-hq-$VERSION.zip"
 )
 all_artifacts=("${portables[@]}")
 for f in "${extras[@]}"; do