Invoice tip prompt option

Design Files invoicing doesn't currently offer a client tipping option. This might seem minor, but it's actually meaningful to my business. HoneyBook includes a tip prompt, and I'm happy to say my clients have used it. That's real revenue that likely wouldn't have happened without the nudge clients may not think to tip on their own, but when the option is right there, it invites them to act on their appreciation.

I'd love to see this feature added to Design Files. It's a small button with a big impact.