feat: refine nightdrive world and authored car

Integrate the Blender grand tourer with a cohesive shader-driven road, terrain, atmosphere, lighting, and post-processing pass. Refine responsive drive dynamics and sign lifecycle behavior, and add durable visual, accessibility, and performance verification evidence.

docs/reviews/evidence/nightdrive-iteration/final/devtools-profile.json

@@ -0,0 +1,46 @@
+{
+  "capturedAt": "2026-09-02",
+  "viewport": {
+    "width": 375,
+    "height": 844,
+    "pixelRatio": 1
+  },
+  "renderer": {
+    "toneMapping": "ACESFilmicToneMapping",
+    "toneMappingExposure": 1.05,
+    "outputColorSpace": "srgb",
+    "drawCalls": 19,
+    "triangles": 15658,
+    "points": 160,
+    "lines": 4490,
+    "programs": 12
+  },
+  "performanceMonitor": {
+    "durationSeconds": 5,
+    "averageFps": 123.5,
+    "minimumFps": 73.5,
+    "averageFrameTimeMs": 8.1,
+    "p95FrameTimeMs": 12.4,
+    "p99FrameTimeMs": 13.2,
+    "spikes": 0,
+    "janks": 0
+  },
+  "memory": {
+    "geometries": 22,
+    "materials": 22,
+    "textures": 2,
+    "estimatedGeometry": "540.3 KB",
+    "estimatedTextures": "1.0 MB",
+    "estimatedTotal": "1.5 MB"
+  },
+  "disposal": {
+    "orphanedGeometries": 0,
+    "orphanedTextures": 0
+  },
+  "browserConsoleErrors": 0,
+  "notes": [
+    "The inspector confirmed the named shader-world and authored-car hierarchy.",
+    "The inspector could not auto-discover the closure-owned EffectComposer; source and unit coverage confirm RenderPass, UnrealBloomPass, and final OutputPass ordering.",
+    "The separate authenticated High-tier allocation trace ran at 1440x900, DPR 2, renderer pixel ratio 1.5."
+  ]
+}