feat(api): integrate Sitar API configuration and authentication

.env.example

@@ -21,14 +21,12 @@ KEYCLOAK_FRONTEND_CLIENT_ID=anexo76-frontend
 # ----- Backend -----
 DEBUG=True
 ENVIRONMENT=development
-
 CORE_DB_HOST=postgres-a76
 CORE_DB_PORT=5432
 CORE_DB_NAME=anexo76_core
 CORE_DB_USER=postgres
 CORE_DB_PASSWORD=postgres
 
-
 # ----- Frontend -----
 NODE_ENV=development
 VITE_API_URL=http://localhost:8000/api
@@ -36,3 +34,8 @@ INTERNAL_API_URL=http://backend:8000/api
 VITE_KEYCLOAK_REALM=master
 VITE_KEYCLOAK_URL=http://localhost:8080
 VITE_KEYCLOAK_CLIENT_ID=anexo76-frontend
+
+# ----- Sitar API -----
+SITAR_API_URL=http://api.sitar.aduanasoft.com
+SITAR_API_USER=your_sitar_user
+SITAR_API_PASSWORD=your_sitar_password