skip icon should handle new Xcode 26 icon format

[marcprux]

Xcode 26 introduces a new .icon format:

Untitled.icon
├── Assets
│   └── Butterfly.svg
└── icon.json

The icon.json file looks like:

{
  "fill" : {
    "linear-gradient" : [
      "display-p3:0.36078,0.41961,0.75294,1.00000",
      "srgb:0.23137,0.24706,0.32941,1.00000"
    ]
  },
  "groups" : [
    {
      "layers" : [
        {
          "glass" : true,
          "hidden" : false,
          "image-name" : "Butterfly.svg",
          "name" : "Butterfly"
        }
      ],
      "shadow" : {
        "kind" : "neutral",
        "opacity" : 0.5
      },
      "translucency" : {
        "enabled" : true,
        "value" : 0.5
      }
    }
  ],
  "supported-platforms" : {
    "circles" : [
      "watchOS"
    ],
    "squares" : "shared"
  }
}

We should enhance commands like skip icon --background #5C6BC0-#3B3F54 symbol.svg to have the option to generate this format.

[vdkdamian]

Any news on this? iOS 26 is around the corner.