Clickable logo and product thumbnails in emails
Add an option in Settings > Communications to make images in customer emails clickable:
- **Logo:** a URL field on the Template's header logo so clicking the logo opens the store's website (or any custom link).
- **Product thumbnails:** optionally link product thumbnails in order emails to the product's page on the store.
Need: store owners want their transactional emails to drive customers back to the site. Today the logo and thumbnails are static images, and links are only possible inside text content blocks.