build: baked lighting pass on kit_demo test map

- Restructured kit_demo.tscn from linear demo to enclosed 5.12x5.12 room
  with walls, floor tiles, pillar, beam, doorway, window
- Added WorldEnvironment with ProceduralSky for ambient lighting
- Added DirectionalLight3D (sun key light, 45° angle, shadows enabled)
- Added OmniLight3D (warm interior fill light)
- Added ReflectionProbe for interior specular reflections
  (box projection, room-sized extents)
- Added LightmapGI with balanced quality settings
  (bounces=3, texel_scale=1.0, max_texture_size=2048, denoiser=true)
- Added tool script (kit_demo.gd) that prints bake status in editor
- Added bake_lighting.gd CLI bake script (requires GPU-enabled instance)
- Updated project.godot with reflection atlas and shadow map quality settings

Headless baking note: Godot's standard editor build requires a GPU/display
for LightmapGI.bake(). Open the scene in the Godot editor and click 'Bake
Lightmap' on the LightmapGI node to generate the baked lightmap data.

docs/visuals-architecture.md

@@ -2,14 +2,22 @@
 
 ## Scope
 Art pass, baked lighting, performance profiling, LOD + occlusion culling for the competitive tactical shooter.
-
-## Dependency Chain (Kanban)
-
-```
-t_p3_artkit  (modular wall/floor kit + PBR materials 1K + art style guide)
-    └── t_p3_lighting  (LightmapGI baked lighting + reflection probes)
-           └── t_p3_profile  (perf budget + LOD + occlusion culling)
-```
+|
+|## Dependency Chain (Kanban)
+|
+|```
+|t_p3_artkit  (modular wall/floor kit + PBR materials 1K + art style guide)  ✅ DONE
+|    └── t_p3_lighting  (LightmapGI baked lighting + reflection probes)
+|           └── t_p3_profile  (perf budget + LOD + occlusion culling)
+|```
+|
+|## Deliverables
+|
+|- **Art style guide**: [docs/art-style-guide.md](docs/art-style-guide.md) — visual direction, modular grid specs, material palette, mapping guidelines
+|- **Modular kit scenes**: `client/assets/scenes/modular/` — 11 CSG-based wall/floor/structural pieces + kit_demo showcase scene
+|- **PBR materials**: `client/assets/materials/` — 7 StandardMaterial3D .tres files
+|- **1K textures**: `client/assets/textures/` — 28 procedural PBR maps (basecolor, normal, roughness, metallic × 7 materials)
+|- **Project config**: `client/project.godot` — Godot 4 Forward+ renderer, 128-tick physics, LightmapGI defaults
 
 ## Art Style