Adicionar botão Interromper no terminal e corrigir botão Retomar

- Botão Interromper na toolbar do terminal para matar execuções ativas
- Endpoint POST /executions/cancel-all para cancelar agentes e pipelines
- Botão aparece/esconde automaticamente conforme execuções ativas
- Corrigir condição do botão Retomar para pipelines antigas sem failedAtStep

public/index.html

@@ -481,6 +481,10 @@
                   <span class="ws-indicator ws-indicator--disconnected" id="terminal-ws-dot"></span>
                   <span id="terminal-ws-label">Desconectado</span>
                 </div>
+                <button class="btn btn--danger btn--sm btn--icon-text" type="button" id="terminal-stop-btn" aria-label="Interromper execução" hidden>
+                  <i data-lucide="square"></i>
+                  <span>Interromper</span>
+                </button>
                 <button class="btn btn--ghost btn--sm btn--icon-text" type="button" id="terminal-clear-btn" aria-label="Limpar terminal">
                   <i data-lucide="trash-2"></i>
                   <span>Limpar</span>

public/js/api.js

@@ -118,6 +118,7 @@ const API = {
     status() { return API.request('GET', '/system/status'); },
     info() { return API.request('GET', '/system/info'); },
     activeExecutions() { return API.request('GET', '/executions/active'); },
+    cancelAll() { return API.request('POST', '/executions/cancel-all'); },
   },
 
   settings: {

public/js/app.js

@@ -555,6 +555,18 @@ const App = {
 
     on('pipeline-execute-submit', 'click', () => PipelinesUI._executeFromModal());
 
+    on('terminal-stop-btn', 'click', async () => {
+      try {
+        await API.system.cancelAll();
+        Terminal.stopProcessing();
+        Terminal.addLine('Todas as execuções foram interrompidas.', 'error');
+        Toast.warning('Execuções interrompidas');
+        App._updateActiveBadge();
+      } catch (err) {
+        Toast.error(`Erro ao interromper: ${err.message}`);
+      }
+    });
+
     on('terminal-clear-btn', 'click', () => {
       Terminal.clear();
       Terminal.disableChat();
@@ -960,6 +972,9 @@ const App = {
       if (countEl) countEl.textContent = count;
       if (badge) badge.style.display = count > 0 ? 'flex' : 'none';
 
+      const stopBtn = document.getElementById('terminal-stop-btn');
+      if (stopBtn) stopBtn.hidden = count === 0;
+
       const terminalSelect = document.getElementById('terminal-execution-select');
       if (terminalSelect && Array.isArray(active)) {
         const existing = new Set(

public/js/components/history.js

@@ -102,7 +102,7 @@ const HistoryUI = {
             <i data-lucide="eye"></i>
             Ver detalhes
           </button>
-          ${(exec.status === 'error' && exec.type === 'pipeline' && exec.failedAtStep !== undefined) ? `
+          ${(exec.status === 'error' && exec.type === 'pipeline') ? `
           <button class="btn btn-ghost btn-sm" data-action="resume-pipeline" data-id="${exec.id}" type="button" title="Retomar do passo ${(exec.failedAtStep || 0) + 1}">
             <i data-lucide="play"></i>
             Retomar