Examine source code of TimerClock

{
  "manifest_version": 3,
  "name": "TimerClock",
  "version": "1.0.0",
  "description": "Timer and stopwatch tool. Countdown timer with notifications and stopwatch.",
  "icons": {
    "48": "clock-icons/icon-48.png",
    "96": "clock-icons/icon-96.png",
    "128": "clock-icons/icon-128.png"
  },
  "action": {
    "default_icon": {
      "48": "clock-icons/icon-48.png",
      "96": "clock-icons/icon-96.png"
    },
    "default_title": "TimerClock",
    "default_popup": "clock-ui/timer.html"
  },
  "permissions": [
    "notifications",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "timerclock@timer.stopwatch",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}