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

pos/migrations/v3.5_whatsapp_state_machine.sql

@@ -10,9 +10,12 @@
 -- To apply manually on a tenant with WhatsApp tables:
 --   psql <tenant_db> -f pos/migrations/v3.5_whatsapp_state_machine.sql
 -- (Remove the ': SKIP' line above before manual execution.)
+--
+-- 2026-10-11: fixed nested dollar-quoting (the outer DO used $$ and the inner
+-- trigger function also used $$, which broke the parser). Now $do$ / $fn$.
 -- ============================================================
 
-DO $$
+DO $do$
 BEGIN
     -- 1. Extender whatsapp_sessions con estado y contexto
     IF EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = 'whatsapp_sessions') THEN
@@ -41,12 +44,12 @@ BEGIN
         CREATE INDEX IF NOT EXISTS idx_wa_cust_link_customer ON wa_customer_links(customer_id);
 
         CREATE OR REPLACE FUNCTION update_wa_link_timestamp()
-        RETURNS TRIGGER AS $$
+        RETURNS TRIGGER AS $fn$
         BEGIN
             NEW.updated_at = NOW();
             RETURN NEW;
         END;
-        $$ LANGUAGE plpgsql;
+        $fn$ LANGUAGE plpgsql;
 
         DROP TRIGGER IF EXISTS trg_wa_link_updated ON wa_customer_links;
         CREATE TRIGGER trg_wa_link_updated
@@ -115,4 +118,4 @@ BEGIN
         FROM wa_customer_links wcl
         WHERE ws.phone = wcl.phone AND ws.customer_id IS NULL;
     END IF;
-END $$;
+END $do$;