Mejoras de sesion: estabilizacion, IA, Nexus Yonke y marketplace B2B

- F0 blindaje: Redis/Celery, pg_hba sin trust LAN, secretos a env 600, backups, webhook auth, jobs muertos
- F1 caja: bugs POS, reembolsos al corte, apartados, CFDI, topes de descuento en cotizacion/apartado
- F2/F7 IA de catalogo: autocategorizacion, dedup de SKUs con embeddings, OCR de facturas, descripciones, claves SAT, limpieza de fitment
- F3 IA en el flujo: vision Yonke, preguntas MeLi, venta cruzada, anomalias, sinonimos, busqueda semantica (rerank/embeddings)
- F4/F8 escala y cartera: /metrics+Prometheus+Grafana, pool, score de credito, churn, metricas multi-tenant
- Nexus Yonke (M1-M6): modelo de datos 1-de-1, alta por donador, vitrina publica, MeLi usado, consignacion, garantia por dias, reportes, etiquetas
- Marketplace B2B entre yonkes (catalogo + pedidos cross-tenant)
- Seguridad: auth en /api/admin/* (35 endpoints), alertas por tenant
- Migraciones v4.27/v4.28; timers expire-demos y rollup-metrics

scripts/meli_sync_all.py

@@ -0,0 +1,48 @@
+#!/usr/bin/env python3
+"""Run MercadoLibre sync (stock/price + orders) for all enabled tenants.
+
+Called by systemd timer every 15 minutes. Runs the Celery task bodies
+synchronously in-process (no broker needed from the timer context).
+"""
+
+import os
+import sys
+
+sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)), '..', 'pos'))
+
+import psycopg2  # noqa: E402
+
+MASTER_DB = os.environ.get('MASTER_DB_NAME', 'nexus_autoparts')
+
+
+def main():
+    conn = psycopg2.connect(dbname=MASTER_DB)
+    cur = conn.cursor()
+    cur.execute("""
+        SELECT t.id FROM tenants t
+        JOIN tenant_schema_version v ON v.tenant_id = t.id
+        WHERE t.is_active
+        ORDER BY t.id
+    """)
+    tenant_ids = [r[0] for r in cur.fetchall()]
+    cur.close()
+    conn.close()
+
+    from tasks import sync_meli_stock_price_task, sync_meli_orders_task
+
+    for tid in tenant_ids:
+        try:
+            r1 = sync_meli_stock_price_task.run(tid)
+            r2 = sync_meli_orders_task.run(tid)
+            print(f'[tenant {tid}] stock={r1} orders={r2}', flush=True)
+        except Exception as e:
+            # Meli disabled / not connected for this tenant is the common case
+            msg = str(e)
+            if 'not configured' in msg or 'not connected' in msg:
+                continue
+            print(f'[tenant {tid}] ERROR: {msg[:200]}', flush=True)
+    print('MeLi sync round complete.', flush=True)
+
+
+if __name__ == '__main__':
+    main()