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

systemd/nexus-backup.service

@@ -1,11 +1,15 @@
 [Unit]
-Description=Nexus Autoparts automated backup
+Description=Nexus Autoparts automated backup (master + all tenant DBs)
 After=postgresql.service
+OnFailure=nexus-alert@%n.service
 
 [Service]
 Type=oneshot
 User=root
 WorkingDirectory=/home/Autopartes
-ExecStart=/bin/bash /home/Autopartes/scripts/backup.sh
+ExecStart=/bin/bash /home/Autopartes/scripts/backup_selective.sh
+Environment=RETENTION_DAYS=21
+Environment=MASTER_DB=nexus_autoparts
+# Environment=BACKUP_S3_BUCKET=mi-bucket   (requiere tools/bin/aws configurado)
 StandardOutput=append:/var/log/nexus-pos/backup.log
 StandardError=append:/var/log/nexus-pos/backup.log

systemd/nexus-expire-demos.service

@@ -0,0 +1,11 @@
+[Unit]
+Description=Nexus demo expiry (downgrade ended demos to free)
+After=postgresql.service
+
+[Service]
+Type=oneshot
+User=postgres
+Environment=MASTER_DB_NAME=nexus_autoparts
+WorkingDirectory=/home/Autopartes
+ExecStart=/usr/bin/python3 /home/Autopartes/scripts/expire_demos.py --apply
+OnFailure=nexus-alert@%n.service

systemd/nexus-expire-demos.timer

@@ -0,0 +1,9 @@
+[Unit]
+Description=Expire ended demo tenants daily
+
+[Timer]
+OnCalendar=*-*-* 03:37:00
+Persistent=true
+
+[Install]
+WantedBy=timers.target

systemd/nexus-pos.service

@@ -18,6 +18,7 @@ Environment=REDIS_URL=redis://localhost:6379/0
 Environment=REDIS_ENABLED=true
 Environment=MEILI_URL=http://localhost:7700
 Environment=MEILI_ENABLED=true
+Environment=MEILI_API_KEY=ac66d5e44381fa0c4c2f949d7026fa19cb8c454a0740262403f27cd76aefed1e
 Environment=QWEN_API_URL=https://api.nan.builders/v1
 Environment=QWEN_API_KEY=sk-Yr0e-Y4F4j1NuuK8xdbxIA
 Environment=QWEN_MODEL=qwen3.6

systemd/nexus-rollup-metrics.service

@@ -0,0 +1,10 @@
+[Unit]
+Description=Nexus tenant metrics rollup (portfolio)
+After=postgresql.service
+
+[Service]
+Type=oneshot
+User=postgres
+WorkingDirectory=/home/Autopartes
+ExecStart=/usr/bin/python3 /home/Autopartes/scripts/rollup_tenant_metrics.py --days 3
+OnFailure=nexus-alert@%n.service

systemd/nexus-rollup-metrics.timer

@@ -0,0 +1,9 @@
+[Unit]
+Description=Roll up per-tenant business metrics daily
+
+[Timer]
+OnCalendar=*-*-* 04:07:00
+Persistent=true
+
+[Install]
+WantedBy=timers.target

systemd/nexus.service

@@ -3,6 +3,8 @@ Description=Nexus Autoparts Dashboard
 After=network.target postgresql.service
 
 [Service]
+# Número WhatsApp público para botón de cotización del catálogo (formato: 521234567890)
+Environment=PUBLIC_WA_NUMBER=
 Type=simple
 User=root
 WorkingDirectory=/home/Autopartes/dashboard