feat: agregar contrato 050 (PARTICULAR COLEGAS) — va a RDA, no a Ventas

Contrato 050 agrupa ~30 laboratorios y clínicas externas (CMXC/LHXC).
Debe enviarse a RDA pero no a Ventas.

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

app/routes/contratos.py

@@ -54,6 +54,7 @@ _SEED = [
     ("040",      "",          "11", "MARTHA LILIANA SALGAR GALLEGO", 1, 1, 0),
     ("041",      "",          "11", "GENCELL PHARMA S.A.S",   1, 0, 1),
     ("042",      "",          "07", "AXA COLPATRIA HYC",      1, 0, 1),
+    ("050",      "",          "11", "PARTICULAR COLEGAS",     0, 0, 1),
 ]