Examine source code of Sheet Music Composer

{
  "manifest_version": 3,
  "name": "Sheet Music Composer",
  "version": "1.0.0",
  "description": "A Firefox addon for composing and creating sheet music easily. Perfect for musicians and composers. Learn more at Elite Piano - https://elitepiano.vn",
  "browser_specific_settings": {
    "gecko": {
      "id": "sheet-music-composer@elitepiano.vn",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "activeTab",
    "scripting",
    "storage"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_title": "Sheet Music Composer",
    "default_icon": {
      "16": "images/icon-16.png",
      "48": "images/icon-48.png",
      "128": "images/icon-128.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end",
      "match_about_blank": false
    }
  ],
  "icons": {
    "16": "images/icon-16.png",
    "48": "images/icon-48.png",
    "128": "images/icon-128.png"
  },
  "homepage_url": "https://elitepiano.vn"
}