Notify stores about newly registered works

Zindies has been informing about newly registered works via the app's general 'notifications'. However, we hadn't been sending those updates by email. In particular, since stores often want to know about new works, we've decided to start emailing them. Unlike notifications, emails remain in the mailbox, so they're easier to review later. I'll write more details separately on note, but the email content varies depending on whether we already carry works by the creator. If we already carry them, stores can contact the creator right away. If not, the email explains our stance on carrying their work. This isn't a major feature addition, but I hope it becomes an opportunity for creators and stores to interact.