ScoreboardState folds the six live-chat event kinds into the numbers a creator puts on screen:
last member, last Super Chat, last gift, members gained, milestones, and session money per
currency. Scope is the running session (creator ruling): reset at start, dead at End, no
persistence.
Two rules are load-bearing:
- money is keyed by currency and never summed across them; the tile shows the dominant currency by
VALUE, so a single EUR tip cannot flip the display away from the larger USD total
- a gifted membership is counted ONCE, from membershipGiftingEvent (which carries the count);
giftMembershipReceivedEvent is the recipient's view of the same purchase and changes nothing.
The test fires five recipient events after one purchase of five and the total must not move.
