improvement: v1 standalone treatment/case creation made possible.

backend/src/modules/appointments/appointments.service.ts

@@ -344,9 +344,9 @@ export class AppointmentsService {
   private async ensurePatientInOrg(patientId: string, _organizationId: string) {
     const patient = await this.prisma.patient.findUnique({
       where: { id: patientId },
-      select: { id: true },
+      select: { id: true, isWalkIn: true },
     });
-    if (!patient) {
+    if (!patient || patient.isWalkIn) {
       throw new AppException(ErrorCode.PATIENT_NOT_FOUND, HttpStatus.NOT_FOUND);
     }
   }