feat: send email notifications for missed messages

- New cron job in cluster
- Handle presence and other concerns
- Toggle in app to disable email notifications
- Handles other edge cases such as cooldown period
- Simple html email with simple message

Closes #117

go/cmd/orion/main.go

@@ -122,6 +122,9 @@ func main() {
 	mux.Handle("POST /auth/sign-out", withAuth(h.SignOut))
 	mux.Handle("GET /auth/me", withAuth(h.GetCurrentHuman))
 
+	// Settings
+	mux.Handle("PATCH /humans/me/settings", withAuth(h.UpdateSettings))
+
 	// Networks
 	mux.Handle("POST /networks", withAuth(h.CreateNetwork))
 	mux.Handle("GET /networks", withAuth(h.ListNetworks))