feat: Integrar AuditService en todos los endpoints críticos

- Auth: login, logout, login_failed con registro automático
- Tickets: create, update, delete, assign con old/new values
- Users: create, update, delete con sanitización de passwords
- Stats: implementar top_users con JOIN a tabla users
- Schema: agregar índices compuestos para mejor performance
- Frontend: limpiar logs de debug en viewDetail
- Manejo de errores: audit logs no afectan flujo principal

db/schema.sql

@@ -369,10 +369,14 @@ CREATE TABLE audit_logs (
 CREATE INDEX idx_audit_logs_tenant_id ON audit_logs(tenant_id);
 CREATE INDEX idx_audit_logs_user_id ON audit_logs(user_id);
 CREATE INDEX idx_audit_logs_action ON audit_logs(action);
-CREATE INDEX idx_audit_logs_resource ON audit_logs(resource_type, resource_id);
 CREATE INDEX idx_audit_logs_correlation_id ON audit_logs(correlation_id);
 CREATE INDEX idx_audit_logs_created_at ON audit_logs(created_at);
 
+-- Índices compuestos para queries comunes de auditoría
+CREATE INDEX idx_audit_logs_tenant_action ON audit_logs(tenant_id, action);
+CREATE INDEX idx_audit_logs_resource ON audit_logs(resource_type, resource_id);
+CREATE INDEX idx_audit_logs_user_created ON audit_logs(user_id, created_at);
+
 -- ===================================
 -- FUNCIONES Y TRIGGERS
 -- ===================================