Examine source code of Typing Duel

{
  "manifest_version": 2,
  "name": "Typing Duel",
  "version": "1.3",
  "description": "Local PvP typing duel in popup. Peer-to-peer via manual signal exchange — no server required.",
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_title": "Typing Duel",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "typingduel@example.com",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  }
}