[CRIT-002] feat(ddl): Add public.set_updated_at() function

Create missing trigger function required by MLM schema triggers.
The function updates the updated_at column to CURRENT_TIMESTAMP
on row updates for mlm.structures, mlm.ranks, and mlm.nodes tables.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ddl/03-functions.sql

@@ -162,6 +162,22 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql;
 
+-- =============================================================================
+-- FUNCION: public.set_updated_at()
+-- Trigger function para actualizar columna updated_at automaticamente
+-- Usada por: mlm.structures, mlm.ranks, mlm.nodes (schema mlm)
+-- Nota: Equivalente a update_updated_at_column() - mantener ambas por compatibilidad
+-- =============================================================================
+CREATE OR REPLACE FUNCTION public.set_updated_at()
+RETURNS TRIGGER AS $$
+BEGIN
+    NEW.updated_at = CURRENT_TIMESTAMP;
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+COMMENT ON FUNCTION public.set_updated_at() IS 'Trigger function que actualiza automaticamente la columna updated_at al timestamp actual';
+
 -- Create AI configs updated_at trigger (table defined in schemas/ai/)
 DO $$
 BEGIN