feat(stats): voice-time and message leaderboards per space

Voice stays get their own table rather than joining the audit log: that table
records points in time, a call is an interval, and pairing join/leave point
events would leave every query guessing at joins whose leave never arrived.

Sessions are opened and closed inside joinRoom/leaveCurrentRoom rather than at
the seven call sites that reach them, so no path can be missed, and
destroyRoom closes them too — it bypasses leaveCurrentRoom and would otherwise
leak open rows.

A restart leaves sessions open with an unknowable end time. They are closed at
startedAt, discarding that time rather than inventing it: crediting the gap
would hand someone hours they never spent, and the numbers are the point.
Mirrors the existing users.status sweep on boot.

Only closed sessions count, so a figure does not move on every refresh. Bars
scale to the leader, not the total — with five people every share of a total
looks identical. Statistics are readable by any member, since they are the
group's own numbers; the audit log, which names who did what, stays on
MANAGE_SPACE.

packages/web/src/i18n/locales/pt-BR.ts

@@ -32,6 +32,20 @@ export const ptBR: Partial<Dictionary> = {
   'settings.voice.micTest.idle': 'Teste seu microfone sem entrar numa call.',
   'settings.voice.micTest.failed': 'Não foi possível abrir o microfone. Verifique o dispositivo e a permissão.',
 
+  // Estatísticas
+  'stats.title': 'Estatísticas',
+  'stats.range.7': 'Últimos 7 dias',
+  'stats.range.30': 'Últimos 30 dias',
+  'stats.range.365': 'Último ano',
+  'stats.voice.title': 'Tempo em call',
+  'stats.messages.title': 'Mensagens enviadas',
+  'stats.empty': 'Nada registrado neste período ainda.',
+  'stats.total.voice': '{value} no total',
+  'stats.total.messages': '{value} mensagens no total',
+  'stats.hours': '{hours}h {minutes}min',
+  'stats.minutes': '{minutes}min',
+  'stats.note': 'A contagem começou quando esta funcionalidade foi instalada — atividade anterior não entra.',
+
   // Registro de auditoria
   'audit.title': 'Registro de auditoria',
   'audit.empty': 'Nada registrado ainda. Mudanças no servidor aparecem aqui.',