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.

src/scene/render-quality.ts

@@ -14,31 +14,31 @@ export interface RenderQualitySettings {
 const settings: Readonly<Record<LiveQualityTier, Omit<RenderQualitySettings, 'pixelRatio'> & { dprCap: number }>> = {
   high: {
     dprCap: 1.5,
-    roadSegments: 192,
-    terrainSegments: 96,
+    roadSegments: 224,
+    terrainSegments: 112,
     terrainOctaves: 3,
-    starCount: 384,
-    streakCount: 48,
+    starCount: 760,
+    streakCount: 112,
     postScale: 1,
     postEffects: true,
   },
   medium: {
     dprCap: 1.5,
-    roadSegments: 144,
-    terrainSegments: 64,
+    roadSegments: 168,
+    terrainSegments: 80,
     terrainOctaves: 2,
-    starCount: 192,
-    streakCount: 28,
+    starCount: 420,
+    streakCount: 64,
     postScale: 0.7,
     postEffects: true,
   },
   low: {
     dprCap: 1.25,
-    roadSegments: 96,
-    terrainSegments: 32,
+    roadSegments: 112,
+    terrainSegments: 48,
     terrainOctaves: 1,
-    starCount: 64,
-    streakCount: 12,
+    starCount: 160,
+    streakCount: 28,
     postScale: 0,
     postEffects: false,
   },