Examine source code of WebTyping

{
  "manifest_version": 3,
  "name": "WebTyping",
  "version": "1.5.0",
  "description": "Turn the current page into a private typing trainer.",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "activeTab",
    "scripting",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "action": {
    "default_title": "Start or close WebTyping",
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png"
    }
  },
  "commands": {
    "toggle-webtyping": {
      "suggested_key": {
        "default": "Alt+Shift+T"
      },
      "description": "Start or close WebTyping"
    }
  },
  "content_security_policy": {
    "extension_pages": "script-src 'self'; object-src 'self'"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "webtyping@local",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      },
      "strict_min_version": "121.0"
    }
  }
}