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>

game/presentation/cockpit/cockpit_practical_lighting.gd

@@ -9,6 +9,10 @@ const CockpitMeshFactory = preload(
 	"res://game/presentation/cockpit/cockpit_mesh_factory.gd"
 )
 
+const CockpitPressureBulkhead = preload(
+	"res://game/presentation/cockpit/cockpit_pressure_bulkhead.gd"
+)
+
 const CAGE_LAMP_SCENE = preload("res://game/presentation/cockpit/assets/models/cage_lamp.glb")
 
 ## Flange centre of the right-hand lamp, on the flat end cap of the pressure
@@ -34,6 +38,7 @@ const WARM_LAMP_SHADOW_BIAS := 0.03
 var _materials: CockpitMaterialPalette
 var _warm_lights: Array[OmniLight3D] = []
 var _emergency_light: OmniLight3D
+var _porthole_fill: OmniLight3D
 
 
 func _init(materials: CockpitMaterialPalette) -> void:
@@ -103,7 +108,20 @@ func _add_fill_light() -> void:
 	porthole_fill.light_energy = 1.0
 	porthole_fill.omni_range = 1.1
 	porthole_fill.shadow_enabled = false
+	# 30 cm behind the glass, it would mirror itself as a hard blue point.
+	porthole_fill.light_cull_mask &= ~CockpitPressureBulkhead.PORTHOLE_GLASS_RENDER_LAYER_BIT
 	add_child(porthole_fill)
+	_porthole_fill = porthole_fill
+
+
+func fill_light_ignores_porthole_glass() -> bool:
+	return (
+		_porthole_fill != null
+		and (
+			_porthole_fill.light_cull_mask
+			& CockpitPressureBulkhead.PORTHOLE_GLASS_RENDER_LAYER_BIT
+		) == 0
+	)
 
 
 func _add_emergency_light() -> void: