[FEATURE] Add an icon url field

[justjam2013]

Add a icon url field to the package.json spec, which would be returned in the search results.

So, using the example result from a search below, a field would be returned in the package object:

{
  "objects": [
    {
      "downloads": {
        "monthly": 17877,
        "weekly": 3863
      },
      "dependents": "177",
      "updated": "2025-12-22T14:06:11.084Z",
      "searchScore": 294.53653,
      "package": {
        "name": "homebridge-lib",
        "keywords": [
          "homekit",
          "homebridge"
        ],
        "version": "7.2.0",
        "description": "Library for homebridge plugins",
        "sanitized_name": "homebridge-lib",
        "icon": "homepage": "https://github.com/ebaauw/homebridge-lib/path/to/icon_file.png",
        "publisher": {
          "email": "erik.baauw@xs4all.nl",
          "username": "ebaauw"
        },
        "maintainers": [
          {
            "email": "erik.baauw@xs4all.nl",
            "username": "ebaauw"
          }
        ],
        "license": "Apache-2.0",
        "date": "2025-12-08T13:57:14.187Z",
        "links": {
          "homepage": "https://github.com/ebaauw/homebridge-lib#readme",
          "repository": "git+https://github.com/ebaauw/homebridge-lib.git",
          "bugs": "https://github.com/ebaauw/homebridge-lib/issues",
          "npm": "https://www.npmjs.com/package/homebridge-lib"
        }
      },
      "score": {
        "final": 294.53653,
        "detail": {
          "popularity": 1,
          "quality": 1,
          "maintenance": 1
        }
      },
      "flags": {
        "insecure": 0
      }
    }
  ],
  "total": 1,
  "time": "2025-12-25T20:42:48.227Z"
}