Examine source code of CUM - Claude Usage Meter

{
  "manifest_version": 2,
  "name": "Claude Usage Meter",
  "version": "0.1.1",
  "description": "Shows Claude usage, reset timing, and estimated conversation and daily tokens below the Claude composer.",
  "icons": {
    "48": "icons/joker-48.png",
    "96": "icons/joker-96.png"
  },
  "permissions": [
    "alarms",
    "storage",
    "https://claude.ai/*",
    "https://www.claude.ai/*"
  ],
  "background": {
    "scripts": [
      "src/lib/tokenizer.js",
      "src/background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://claude.ai/*",
        "https://www.claude.ai/*"
      ],
      "js": [
        "src/content.js"
      ],
      "css": [
        "src/styles.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "claude-usage-meter@local",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}