Examine source code of Dumbdown

{
  "manifest_version": 3,
  "name": "Dumbdown",
  "version": "2.1.0",
  "description": "AI TL;DR as a shortcut",
  "browser_specific_settings": {
    "gecko": {
      "id": "{318cc47b-72d3-4e6e-bb60-3077a82a603b}",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "host_permissions": [
    "https://chatgpt.com/*",
    "https://claude.ai/*",
    "https://www.perplexity.ai/*"
  ],
  "action": {
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    },
    "default_title": "Summarize with LLM"
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "options_ui": {
    "page": "options/options.html",
    "open_in_tab": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    },
    {
      "matches": [
        "https://chatgpt.com/*",
        "https://claude.ai/*",
        "https://www.perplexity.ai/*"
      ],
      "js": [
        "inject.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "commands": {
    "_execute_action": {
      "suggested_key": {
        "default": "Alt+Shift+S",
        "linux": "Ctrl+Shift+Y",
        "mac": "Command+Shift+S"
      },
      "description": "Summarize with default LLM"
    },
    "summarize-perplexity": {
      "suggested_key": {
        "default": "Alt+Shift+P",
        "linux": "Ctrl+Shift+O",
        "mac": "Command+Shift+P"
      },
      "description": "Summarize with Perplexity"
    },
    "summarize-chatgpt": {
      "suggested_key": {
        "default": "Alt+Shift+G",
        "linux": "Ctrl+Shift+U",
        "mac": "Command+Shift+G"
      },
      "description": "Summarize with ChatGPT"
    },
    "summarize-claude": {
      "suggested_key": {
        "default": "Alt+Shift+C",
        "linux": "Ctrl+Shift+L",
        "mac": "Command+Shift+C"
      },
      "description": "Summarize with Claude"
    }
  }
}