Attribute completed speaker time to the correct participant

Meeting 14 Chrome acceptance had Deputy 02 sign up, speak for about 1:42, and stop normally. After stopping, D02 disappeared from the speaker display and the 1:42 completed duration appeared beside Councillor 01. Preserve speaker identity across start/stop broadcasts and completed-list rendering, especially for deputies activated by ongoing participant changes. Add browser/view coverage with queued councillors plus a deputy speaker and assert timer/history attribution after stop and meeting end.