Marks the invoice as sent and emails the homeowner a PDF copy. Use it when the invoice is final and ready for the customer.

• A draft invoice moves to sent; any other status is left as it is.
• A PDF of the invoice is saved to the job's documents the first time it is sent.
• The email only goes out if the job's contact has an email address and has opted in to email. Otherwise the invoice is still marked sent, and message says that no email was sent.
• The email is delivered in the background, so a 200 means it was queued, not delivered.
• The token's role must be able to view all company records, or the token's user must have created the invoice. The token needs the write scope.