feat(subject): 参与者状态依赖筛选日期并支持后续编辑

- 未填写筛选日期的参与者不再默认进入 SCREENING，状态显示为占位符。
- SubjectUpdate 不再开放 status 入参，改由后端依据日期推导，并新增
  screening_date 字段允许 PM/CRA 后续补录筛选日期。
- 参与者管理页与详情页同步：详情页支持编辑筛选日期，列表页与详情页
  在没有筛选日期时显示占位符而非旧 enum 值。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/views/ia/SubjectManagement.vue

@@ -85,7 +85,7 @@
             <template #default="scope">{{ displayDate(scope.row.consent_date) }}</template>
           </el-table-column>
           <el-table-column prop="status" :label="TEXT.common.fields.status">
-            <template #default="scope">{{ displayEnum(TEXT.enums.subjectStatus, scope.row.status) }}</template>
+            <template #default="scope">{{ displaySubjectStatus(scope.row) }}</template>
           </el-table-column>
           <el-table-column prop="enrollment_date" :label="TEXT.common.fields.enrollmentDate">
             <template #default="scope">{{ displayDate(scope.row.enrollment_date) }}</template>
@@ -227,6 +227,10 @@ const getAeBadges = (row: any) => {
   }
   return badges;
 };
+const displaySubjectStatus = (subject: any) => {
+  if (!subject?.screening_date) return TEXT.common.fallback;
+  return displayEnum(TEXT.enums.subjectStatus, subject.status);
+};
 const filteredItems = computed(() => {
   const keyword = filters.value.keyword.trim().toLowerCase();
   return items.value.filter((item) => {

frontend/src/views/subjects/SubjectDetail.vue

@@ -30,9 +30,18 @@
         <el-descriptions-item :label="TEXT.modules.subjectManagement.screeningNo">{{ detail.subject_no || TEXT.common.fallback }}</el-descriptions-item>
         <el-descriptions-item :label="TEXT.common.fields.site">{{ siteMap[detail.site_id] || TEXT.common.fallback }}</el-descriptions-item>
         <el-descriptions-item :label="TEXT.common.fields.status">
-          <span>{{ displayEnum(TEXT.enums.subjectStatus, detail.status) }}</span>
+          <span>{{ displaySubjectStatus(detail) }}</span>
+        </el-descriptions-item>
+        <el-descriptions-item :label="TEXT.common.fields.screeningDate">
+          <el-date-picker
+            v-if="subjectEditing"
+            v-model="subjectForm.screening_date"
+            type="date"
+            value-format="YYYY-MM-DD"
+            size="small"
+          />
+          <span v-else>{{ displayDate(detail.screening_date) }}</span>
         </el-descriptions-item>
-        <el-descriptions-item :label="TEXT.common.fields.screeningDate">{{ displayDate(detail.screening_date) }}</el-descriptions-item>
         <el-descriptions-item :label="TEXT.common.fields.consentDate">
           <el-date-picker
             v-if="subjectEditing"
@@ -532,6 +541,7 @@ const detail = reactive<any>({
 const subjectEditing = ref(false);
 const subjectSaving = ref(false);
 const subjectForm = reactive({
+  screening_date: "",
   enrollment_date: "",
   baseline_date: "",
   consent_date: "",
@@ -665,6 +675,11 @@ const getErrorMessage = (error: any, fallback: string) => {
   return fallback;
 };
 
+const displaySubjectStatus = (subject: any) => {
+  if (!subject?.screening_date) return TEXT.common.fallback;
+  return displayEnum(TEXT.enums.subjectStatus, subject.status);
+};
+
 const loadSites = async () => {
   if (!studyId) return;
   try {
@@ -702,6 +717,7 @@ const startSubjectEdit = () => {
     ElMessage.warning("中心已停用");
     return;
   }
+  subjectForm.screening_date = detail.screening_date || "";
   subjectForm.consent_date = detail.consent_date || "";
   subjectForm.enrollment_date = detail.enrollment_date || "";
   subjectForm.baseline_date = detail.baseline_date || "";
@@ -723,6 +739,7 @@ const saveSubjectEdit = async () => {
   subjectSaving.value = true;
   try {
     const payload = {
+      screening_date: subjectForm.screening_date || null,
       consent_date: subjectForm.consent_date || null,
       enrollment_date: subjectForm.enrollment_date || null,
       baseline_date: subjectForm.baseline_date || null,