Examine source code of Mochi addon

{
  "name": "Mochi addon",
  "description": "An addon for creating mochi flashcards from the web.",
  "version": "1.1",
  "manifest_version": 3,
  "icons": {
    "16": "icon.png",
    "32": "icon.png",
    "48": "icon.png",
    "128": "icon.png"
  },
  "permissions": [
    "storage",
    "contextMenus",
    "activeTab"
  ],
  "host_permissions": [
    "https://app.mochi.cards/*"
  ],
  "action": {
    "default_popup": "popup/index.html",
    "default_icon": "icon.png"
  },
  "background": {
    "service_worker": "background.js",
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "@cards.mochi.web-ext"
    }
  }
}