fix: parallelize WA sync and surface scheduler errors in historial

- whatsapp_sync: send patients concurrently (asyncio.gather + semaphore=10) instead of sequentially — eliminates long waits with many patients
- envios_erp: auto-refresh historial every 60s when scheduler tab is active
- main: wrap scheduler job to catch exceptions and log them to sync_wa_log so failures are visible in historial

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/templates/envios_erp.html

@@ -151,6 +151,7 @@ const _TAB_ACTIVE   = 'border-green-500 text-green-700 bg-green-50';
 const _TAB_INACTIVE = 'border-transparent text-gray-500 hover:text-gray-700 hover:border-gray-300';
 
 let _schedulerLoaded = false;
+let _histRefreshTimer = null;
 
 function switchTab(name) {
     document.querySelectorAll('.tab-panel').forEach(p => p.classList.add('hidden'));
@@ -168,10 +169,17 @@ function switchTab(name) {
         const iframe = document.getElementById('iframe-pacientes');
         if (!iframe.src) iframe.src = '/pacientes?embed=1';
     }
-    if (name === 'scheduler' && !_schedulerLoaded) {
-        _schedulerLoaded = true;
-        cargarHistorialScheduler();
-        pollSchedulerStatus();
+    if (name === 'scheduler') {
+        if (!_schedulerLoaded) {
+            _schedulerLoaded = true;
+            cargarHistorialScheduler();
+            pollSchedulerStatus();
+        }
+        // Auto-refresh historial cada 60s mientras el tab está activo
+        clearInterval(_histRefreshTimer);
+        _histRefreshTimer = setInterval(cargarHistorialScheduler, 60000);
+    } else {
+        clearInterval(_histRefreshTimer);
     }
 
     sessionStorage.setItem('erp-tab', name);