feat: MercadoLibre integration + inventory bulk publish + WhatsApp bridge fixes

- Add MercadoLibre OAuth, listings, orders, webhooks and category search
- New marketplace_external_bp.py, meli_service.py, marketplace_external_service.py
- New marketplace_external.html/js with ML management UI
- Inventory: bulk publish to ML with category autocomplete, listing type and shipping selectors
- Inventory: new .btn--meli styles, select/label CSS fixes
- WhatsApp bridge: rate limiting, 440/515/408 error handling, stale watchdog
- DB migration v3.4_meli_integration.sql for marketplace_listings, orders, sync_queue
- Add Celery tasks for ML sync and webhook processing
- Sidebar: MercadoLibre navigation link

pos/templates/accounting.html

@@ -188,10 +188,10 @@
       <!-- Tabs -->
       <div class="tabs-row" role="tablist">
         <button class="tab-btn is-active" role="tab" aria-selected="true" onclick="switchTab('cxc')">
-          Ctas. por Cobrar <span class="tab-btn__badge">23</span>
+          Ctas. por Cobrar <span class="tab-btn__badge" id="badge-cxc">0</span>
         </button>
         <button class="tab-btn" role="tab" aria-selected="false" onclick="switchTab('cxp')">
-          Ctas. por Pagar <span class="tab-btn__badge--alert tab-btn__badge">3</span>
+          Ctas. por Pagar <span class="tab-btn__badge--alert tab-btn__badge" id="badge-cxp">0</span>
         </button>
         <button class="tab-btn" role="tab" aria-selected="false" onclick="switchTab('balance')">
           Balance General
@@ -498,5 +498,31 @@
   <script src="/pos/static/js/pwa-install.js" defer></script>
 
   <script src="/pos/static/js/chat.js" defer></script>
+
+  <script>
+    // Load accounting stats for tab badges
+    async function loadAccountingStats() {
+      const token = localStorage.getItem('pos_token') || '';
+      try {
+        const res = await fetch('/pos/api/accounting/stats', {
+          headers: token ? { 'Authorization': 'Bearer ' + token } : {}
+        });
+        if (!res.ok) return;
+        const data = await res.json();
+        const map = {
+          'badge-cxc': data.cuentas_cobrar,
+          'badge-cxp': data.cuentas_pagar
+        };
+        Object.entries(map).forEach(function([id, val]) {
+          const el = document.getElementById(id);
+          if (el) el.textContent = val || 0;
+        });
+      } catch (e) {
+        console.error('Failed to load accounting stats:', e);
+      }
+    }
+    window.loadAccountingStats = loadAccountingStats;
+    loadAccountingStats();
+  </script>
 </body>
 </html>