Fix out-of-order pagination responses in the treatment table

pg-prev/pg-next deliberately skip comCarregando (it would fight the
page-boundary disabled-state logic), so nothing stopped two rapid clicks
from firing overlapping GET /api/leads requests. If the earlier page's
response resolved after the later one, it silently overwrote the table,
pager text and prev/next disabled state with a page the operator was no
longer viewing. Adds a per-call sequence number in carregarTabela(); a
response is only applied if no newer call has started since, covering
every caller (pager clicks, filter changes, tab activation) with one guard.

Found via a full-project audit; verified the regression test fails
against the pre-fix code and passes against the fix.

public/js/tratamento.js

@@ -4,6 +4,7 @@ const Tratamento = (() => {
   let totalPages = 1;
   let carregado = false;
   let refreshTimer = null;
+  let tabelaRequestSeq = 0;
 
   const CLASSIFICACAO_LABELS = {
     excelente: 'Excelente', bom: 'Bom', medio: 'Médio', baixo: 'Baixo', muito_baixo: 'Muito Baixo'
@@ -364,7 +365,13 @@ const Tratamento = (() => {
   }
 
   async function carregarTabela() {
+    const requestId = ++tabelaRequestSeq;
     const data = await API.get(`/api/leads?${filtroQuery({ page, pageSize: 50 })}`);
+    // Descarta respostas fora de ordem: pg-prev/pg-next nao usam comCarregando
+    // (ver bindEvents), entao um clique rapido pode disparar uma nova consulta
+    // antes da anterior responder. Sem isso, a resposta mais lenta podia
+    // sobrescrever a tabela/paginacao com uma pagina que ja nao e mais a atual.
+    if (requestId !== tabelaRequestSeq) return;
     totalPages = Math.max(1, Math.ceil(data.total / data.pageSize));
     el('leads-total').textContent = `— ${fmt.format(data.total)} encontrados`;
     el('pg-info').textContent = `página ${data.page} de ${fmt.format(totalPages)}`;