feat: premium hero car + subdued aurora

- Hero car: premium procedural fallback with detailed body, cockpit, wheels, calipers, neon accents, headlights/taillights, underglow
- Lighting: showroom setup with key/fill/rim/accent lights, PCF soft shadows, ACES tone mapping, SRGB color space
- Camera stages: cinematic 3/4 front, side, other side, top-down with FOV interpolation
- Animation: smooth quartic ease-out stage transitions, floating + rotation, floor glow pulse
- Aurora: reduced opacity (0.18/0.08), slower drift (35s/42s), larger softer blobs

Author: Virtual Steering Dev