feat: calculate real discount % from TARIFA vs RELACION.PRECIO

Joins TARIFA using EMPRESA.TARIFA to get the base price per exam,
then calculates descuento = round((sum(TARIFA) - sum(PRECIO)) / sum(TARIFA) * 100)
and sends it as integer percentage in the RDA header encabezado.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/routes/automation.py

@@ -62,6 +62,7 @@ SELECT
     rel.COD_EXAMEN,
     COALESCE(NULLIF(TRIM(ex.NUM_ISS), ''), TRIM(rel.COD_EXAMEN)) AS CUPS,
     rel.PRECIO,
+    COALESCE(t.VALOR, rel.PRECIO) AS PRECIO_TARIFA,
     rel.FECHA_REPORTADO,
     m.COD_ESPECIALIDAD,
     COALESCE(NULLIF(TRIM(m.CODIGO), ''), NULLIF(TRIM(r.USUARIO), ''), '') AS profesional,
@@ -72,6 +73,7 @@ JOIN RELACION rel ON rel.IDRECEPCION = r.IDRECEPCION
 LEFT JOIN EXAMEN ex ON TRIM(ex.CODIGO) = TRIM(rel.COD_EXAMEN)
 LEFT JOIN MEDICO m ON m.CODIGO = r.COD_MEDICO
 LEFT JOIN EMPRESA e ON e.NIT = r.NIT_EMPRESA
+LEFT JOIN TARIFA t ON TRIM(t.COD_EXAMEN) = TRIM(rel.COD_EXAMEN) AND t.TARIFA = e.TARIFA
 WHERE r.FECHA_RECEPCION BETWEEN :fecha_ini AND :fecha_fin
   AND r.NUM_FACTURA > 0
   {filtro_contrato_rda}