The outgoing verification flow had no client side timeout: if the other
session never answered, the screen waited on "Waiting to accept request"
for as long as the user left it open, with no indication that the
request could no longer succeed.
Bound the wait to the ten minutes the Matrix specification gives a
verification request. Past that the other session can no longer accept
it, so cancel the request and move to the canceled state, which already
offers to start again.
hayaksi1
fcecc7acba