chore: code quality audit and lint fixes

- Fix all 63 ESLint errors across codebase
- Consolidate MaterialWithTextureSlots type in src/types/three/three.ts
- Add CSS custom properties for design tokens
- Extract ebike constants to src/data/ebike/ebikeConfig.ts
- Add proper TypeScript types for window extensions
- Fix React hooks violations (refs during render, setState in effects)
- Remove unused exports and redundant CSS
- Add type guards for Three.js material handling
- Clean up AI slop comments and legacy CSS patterns

src/world/Environment.tsx

@@ -37,7 +37,7 @@ export function Environment(): React.JSX.Element {
       {showSky ? (
         <SkyModel
           fallbackColor={GAME_SCENE_FALLBACK_BACKGROUND_COLOR}
-          fallbackModelScale={GAME_SCENE_SKY_FALLBACK_MODEL_SCALE}
+          fallbackScale={GAME_SCENE_SKY_FALLBACK_MODEL_SCALE}
           fallbackModelPath={GAME_SCENE_SKY_FALLBACK_MODEL_PATH}
           modelPath={GAME_SCENE_SKY_MODEL_PATH}
           scale={GAME_SCENE_SKY_MODEL_SCALE}