Fix Bug #491: 【执行科室配置】保存配置时系统报错

后端修复：时间冲突校验时 organizationService.getById 可能返回 null，增加空值判断避免 NPE
前端修复：保存前校验是否已选择科室，未选择时给出提示并阻断

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

openhis-server-new/openhis-application/src/main/java/com/openhis/web/basedatamanage/appservice/impl/OrganizationLocationAppServiceImpl.java

@@ -147,8 +147,8 @@ public class OrganizationLocationAppServiceImpl implements IOrganizationLocation
             for (OrganizationLocation organizationLocation : organizationLocationList)
                 if (DateTimeUtils.isOverlap(organizationLocation.getStartTime(), organizationLocation.getEndTime(),
                     orgLoc.getStartTime(), orgLoc.getEndTime())) {
-                    String organizationName =
-                        organizationService.getById(organizationLocation.getOrganizationId()).getName();
+                    Organization org = organizationService.getById(organizationLocation.getOrganizationId());
+                    String organizationName = org != null ? org.getName() : "未知科室";
                     return R.fail("当前诊疗：" + activityName + CommonConstants.Common.DASH + orgLoc.getStartTime()
                         + CommonConstants.Common.DASH + orgLoc.getEndTime() + "与" + organizationName + "时间冲突");
                 }