Examine source code of Smart Keyword Highlighter

{
  "manifest_version": 3,
  "name": "Smart Keyword Highlighter",
  "version": "1.5",
  "description": "Smart keyword highlighting to improve focus. Uses CSS Custom Highlight API, adaptive contrast, and persistent registry.",
  "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"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "keyword-highlighter@evren.io",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  },
  "permissions": [
    "storage",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_icon": {
      "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"
    },
    "default_title": "Toggle Smart Keyword Highlighter"
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ]
}