Cool idea!

Some custodial slack not, which someone has to run, and where you have to preload some zapping balance at first should work.

/zapbot send 100 sats to @melissa

-> insufficient balance. If you want to zap, load your account with some sats at this lnurl:

When balance loaded, zapbot can probably detect it and send you notification on slack. And then:

/zapbot send 100 sats to @melissa

-> zapped!