Add sunlit shallows site with localized sun shafts

New visual test site under game/world/sites: flat sandy floor at
-40 m, calm surface at 0 m, fixed daytime sun ahead of and above
the submarine. Light shafts come from a shadow-only surface
occluder whose alpha-scissor ripples open only inside a pool a few
tens of metres ahead; a subtractive FogVolume cancels the global
volumetric fog above the water, and an unshaded ceiling mesh shows
the lit underside of the surface inside that pool. A composed
world (sunlit_shallows_world.tscn) mounts the submarine, cockpit
and camera rig in it, with the projectors kept out of the fog.

Cockpit: the porthole glass moves to its own render layer with a
rougher material and the porthole fill light excludes that layer,
so interior lamps no longer mirror as hard specular points.

Quality gate: new integration suite for the site (42 checks), three
glass assertions in the foundation suite, and the Input-access
architecture rule now matches both path separators so the gate runs
on Windows. project.godot raises the volumetric fog froxel grid to
128 so the shafts stay readable.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

scripts/quality_gate.sh

@@ -113,6 +113,16 @@ check_godot_log \
 	"production foundation integration" \
 	"$QUALITY_TEMP_DIRECTORY/foundation-integration-console.log"
 
+printf 'Quality gate: sunlit shallows environment integration\n'
+"$GODOT_EXECUTABLE" --headless \
+	--log-file "$QUALITY_TEMP_DIRECTORY/sunlit-shallows-integration.log" \
+	--path . \
+	--script tests/integration/run_sunlit_shallows_environment.gd \
+	2>&1 | tee "$QUALITY_TEMP_DIRECTORY/sunlit-shallows-integration-console.log"
+check_godot_log \
+	"sunlit shallows environment integration" \
+	"$QUALITY_TEMP_DIRECTORY/sunlit-shallows-integration-console.log"
+
 printf 'Quality gate: POC B integration\n'
 "$GODOT_EXECUTABLE" --headless \
 	--log-file "$QUALITY_TEMP_DIRECTORY/poc_b_integration.log" \