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.

CHANGELOG.md

@@ -4,6 +4,30 @@ All notable user-facing changes to Gig Line. The format follows
 [Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and versions use
 Semantic Versioning.
 
+## [0.7.1] — 2026-11-01
+
+### Added
+
+- An optional Desktop HQ build for Windows and Linux that uses Forward+,
+  volumetric fog and SDFGI, packaged with an `override.cfg` beside the
+  executable.
+- Volumetric flashlight haze in the Desktop HQ build, with a LATE-phase preset
+  tuned so the entrance facade stays readable.
+
+### Changed
+
+- The normal Compatibility build remains the default; the preset only affects
+  the extracted Desktop HQ copy.
+- Night-time light falloff adapts to Godot 4.7 while keeping the 4.3 baseline
+  unchanged.
+
+### Fixed
+
+- The flashlight no longer disappears at night on Godot 4.7 under the old
+  attenuation curve.
+- Headless and Web builds stay non-volumetric and boot normally when Forward+
+  is unavailable.
+
 ## [0.7.0] — 2026-11-01
 
 ### Changed