Examine source code of CountdownTimer

{
  "manifest_version": 3,
  "name": "CountdownTimer",
  "version": "1.0.0",
  "description": "Create countdown timers with presets. Pomodoro technique, breaks, custom timers with notifications and visual progress.",
  "icons": {
    "48": "timer-icons/icon-48.png",
    "96": "timer-icons/icon-96.png",
    "128": "timer-icons/icon-128.png"
  },
  "action": {
    "default_popup": "timer-ui/timer.html",
    "default_title": "CountdownTimer"
  },
  "permissions": [
    "storage",
    "notifications"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "countdowntimer@timer.tool",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}