Incoming webhooks return no message id, so nothing can be removed later.
Settings now take a bot token plus channel, chat.postMessage records channel
and timestamp on the run, and the history carries a delete button per
message. The webhook stays as a fallback and is marked as not deletable.
New settings area: the webhook lives in the database and is only shown
shortened afterwards, the environment variable stays as a fallback. A switch
decides whether internal entries travel, a button sends the digest right
away, and every run is recorded with period, count, projects, result and
who triggered it.
Matthias G