Handle inline svg/png images in url-metadata

[fennifith]

Currently, processImage does not use any inline images it picks up for favicons/banners, and logs the following error:

Error: Request body for data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100'><style>svg {background: transparent;}path {fill: black;}@media (prefers-color-scheme: dark)  {path {fill: white;}}</style><path fill-rule='evenodd' clip-rule='evenodd' d='M81.8182 18.1818V81.8182H18.1818V18.1818H81.8182ZM10 90V10H90V90H10Z'/></svg> is null

processImage should instead detect when an inline svg or base64/png URL is provided, and decode that data instead of calling fetch().