Attachments
Files staged in DNA, uploaded to the tracking provider when the draft note that references them is published.
Stage a file for a note
Store an uploaded file on the backend and return an attachment ID. Put the ID in a draft note's `attachment_ids`; publishing the note uploads the file to the tracking provider and removes the staged copy.
Delete a staged attachment
Delete a staged attachment by ID.
Retrieve a staged attachment
Return the image file for a staged attachment by ID.