rate limit channel creation
context
- we can now automatically create channels
- we don't want attackers to abuse this and starve us of resources
behavior
STUB
- when a phone number tries to create more than 3 channels in 1 week (?)
- then that phone number will be blocked from creating any more channels for a week
open questions:
- should there be a global rate limit (to throttle all channel creation for a week once a certain threshhold has been passed? this would prevent attackers from switching phone numbers to continue abusing. it would also inconvenience users!)
- what should the exact "bucket leak" rate be?
- there are lots of ways to implement rate limits... what way do we want to pick?