* report a reason on room-ended telemetry
Room.Close already took a ParticipantCloseReason, but OnClose was func()
with no arguments, so the reason was structurally dropped before it could
reach RoomEnded.
Add types.RoomCloseReason and carry it through Close -> OnClose -> RoomEnded,
where it lands on both the analytics event and the room_finished webhook.
Room.Close now takes the room reason and derives the participant reason from
it, so the two can never disagree. ToParticipantCloseReason maps each reason
to exactly what its call site passed before, so no participant-facing
behaviour changes; a table test pins that mapping.
* fix(test): update webhook test for RoomCloseReason
test/ was outside the packages checked before pushing, so this Close call
site was missed. Also assert the reason reaches the room_finished webhook,
which the unit test cannot cover since it runs with a nil notifier.