Improve the existing rim-color path into a single-channel refraction field.
The shader derives a continuous rounded-rect normal, caps edge slope, and
uses inward/tangent soft sampling to avoid border tearing and dark flecks.

Content-pull ramp controls keep distorted content closer to the glass edge
while the optical pull still follows the surface profile. Fresnel rim
highlighting and symmetric SDF antialiasing improve edge quality.

Tuned defaults are blurAmount 0.6, ior 1.5, saturation 0.04,
specular 0, and tint 0. Dispersion, edge-saturation, reflection-offset,
and displacement-factor controls are removed because they no longer feed
the shader.

将已有边缘染色路径优化为单通道折射场。
shader 通过连续圆角矩形法线计算折射，限制边缘斜率，并使用
向内/切线柔化采样，减少边界撕裂和深色噪点。

内容贴边渐变控制让变形后的内容更贴近玻璃边缘，
同时光学位移仍跟随表面剖面变化。Fresnel 边缘高光和
对称 SDF 抗锯齿改善边缘质量。

默认值调整为 blurAmount 0.6、ior 1.5、saturation 0.04、
specular 0 和 tint 0。色散、边缘饱和度、反射偏移和
位移强度控制已移除，因为这些参数不再进入 shader。

Log: 优化液态玻璃折射效果
Influence: 需测试圆角边缘、模糊强度、默认颜色参数和 DConfig 加载。

Replace the binary top/side split in getFieldT with a geometric-mean
of two directional bezel progressions (sqrt(smoother01(top) *
smoother01(side))), matching the visualizer's smoothCornerT. The old
approach produced a fold line along the 45° diagonal in corner regions
when radius < bezelWidth, causing incorrect refraction direction and
visible artifacts. The new field is C1-smooth everywhere, ensuring the
gradient (used for the refraction normal and localBezel) is continuous.

修复 radius < bezelWidth 时角区 t 场的折痕 bug：将 getFieldT 中的
top/side 二分改为两个方向进度的几何平均
(sqrt(smoother01(top) * smoother01(side)))，与可视化工具的
smoothCornerT 一致。旧实现在角区沿 45° 对角线产生折痕，导致
折射法线方向错误和可见伪影；新场处处 C1 光滑，梯度连续。

Log: 修复角区 t 场折痕
Influence: radius < bezelWidth 时玻璃折射不再有对角线折痕，
角区折射方向连续平滑。