periodic bot-driven notifications (scheduler)

i wanted to be able to "ask" ai to "notify" me periodically on some things (scheduler)

to achieve this i implemented 3 parts in 3 PRs:
1 new "reply-in-thread" workflow node #328 
2 "scheduler" node and runtime (requires p1 merged to elliminate conflicts when possible) #329 
3 `@pulse` in-app tool which creates workflow from template when user calls it (requires both of them merged) #330 