Support for attachments in Calendar entity (CalendarEvent)

Hi,

I noticed that the current implementation of CalendarEvent does not include support for attachments (reference: link to source code). Attachments feature is part of the iCalendar specification as defined in RFC 5545, which allows attachments to be included as either a URI or a binary blob.

My specific use case involves the LLM Vision integration, which records CCTV events into its Event Calendar. I would like to enhance these calendar entries by attaching relevant media, namely a link to the snapshot image or a video clip, or maybe even inline the image in the event itself.