使用 Three.js 实现神经脉冲网络特效，具体要求：

**核心特效**
- 神经元激活效果
- 神经连接线
- 激活阈值控制
- 颜色方案切换
- 7个实时参数

**场景与光照**
- 深紫渐变背景
- 加法混合发光
- 球体缓慢旋转

**交互与控制**
- OrbitControls 阻尼旋转
- GUI 面板实时调节
- 脉冲速度/神经元密度/连接强度

**技术要求**
- Three.js 版本 (ES Module)
- 自定义 ShaderMaterial
- SphereGeometry 球体
- 随机激活模式

float neurons(vec2 uv, float density) {
    float neuronActivation = 0.0;
    for(int i = 0; i < 15; i++) {
        vec2 neuronPos = vec2(
            noise(vec2(float(i) * 0.234, 0.567)) * 2.0 - 1.0,
            noise(vec2(float(i) * 0.567, 0.891)) * 2.0 - 1.0
        );
        float dist = distance(uv, neuronPos);
        float pulse = sin(uTime * uPulseSpeed + float(i) * 0.5) * 0.5 + 0.5;
        neuronActivation += exp(-dist * 12.0) * pulse * density;
    }
    return neuronActivation;
}

float neuralConnections(vec2 uv, float strength) {
    float connections = 0.0;
    for(int i = 0; i < 8; i++) {
        float angle = float(i) * 3.14159 / 4.0 + uTime * 0.3;
        vec2 dir = vec2(cos(angle), sin(angle));
        float projection = dot(uv, dir);
        float wave = sin(projection * 10.0 + uTime * uPulseSpeed * 2.0);
        connections += abs(wave) * 0.1 * strength;
    }
    return connections;
}

float activation = step(uActivationThreshold, neuronActivation + neuralField * 0.3);