Refract the shard with the ice again and make it bigger

It is sampled at the refracted position like every other sheet, so the
cracks cut across it and bend its silhouette; SHARD 0.70 -> 0.95.

8_ice_scene.frag

@@ -35,7 +35,7 @@ vec3 shardLocal(vec3 p, float phase) {
   p.yz /= vec2(1.0, 1.45);
   return abs(p);
 }
-const float SHARD = 0.70; // how big the shard is in sheet units
+const float SHARD = 0.95; // how big the shard is in sheet units
 // Cross two octahedra: the intersection is an eight-sided gem, so the shard still
 // reads as a cut stone from any angle instead of a flat kite.
 vec3 gemAxes(vec3 l, out vec2 r) {