Step UX-1：通用选择器

frontend/src/views/Verification.vue

@@ -6,7 +6,13 @@
           <el-option label="SDV" value="SDV" />
           <el-option label="SDR" value="SDR" />
         </el-select>
-        <el-input v-model="filters.site_id" placeholder="中心ID" style="width: 180px" @change="load" />
+        <SiteSelect
+          v-model="filters.site_id"
+          :study-id="study.currentStudy?.id || null"
+          placeholder="中心"
+          style="width: 220px"
+          @change="load"
+        />
         <div class="spacer" />
         <el-button v-if="canEdit" type="primary" @click="openCreate">新增进度</el-button>
       </div>
@@ -16,11 +22,15 @@
 
     <el-dialog :title="editForm.id ? '更新进度' : '新增进度'" v-model="showEdit" width="520px">
       <el-form :model="editForm" label-width="120px">
-        <el-form-item label="受试者ID">
-          <el-input v-model="editForm.subject_id" :disabled="!!editForm.id" />
+        <el-form-item label="受试者">
+          <SubjectSelect
+            v-model="editForm.subject_id"
+            :study-id="study.currentStudy?.id || null"
+            :disabled="!!editForm.id"
+          />
         </el-form-item>
-        <el-form-item label="中心ID">
-          <el-input v-model="editForm.site_id" />
+        <el-form-item label="中心">
+          <SiteSelect v-model="editForm.site_id" :study-id="study.currentStudy?.id || null" />
         </el-form-item>
         <el-form-item label="类型">
           <el-select v-model="editForm.level" placeholder="请选择">
@@ -53,6 +63,8 @@ import { fetchVerifications, upsertVerification } from "../api/verifications";
 import { useStudyStore } from "../store/study";
 import { useAuthStore } from "../store/auth";
 import VerificationTable from "../components/VerificationTable.vue";
+import SiteSelect from "../components/selectors/SiteSelect.vue";
+import SubjectSelect from "../components/selectors/SubjectSelect.vue";
 
 const study = useStudyStore();
 const auth = useAuthStore();
@@ -115,7 +127,7 @@ const submitEdit = async () => {
   try {
     await upsertVerification(study.currentStudy.id, {
       subject_id: editForm.value.subject_id,
-      site_id: editForm.value.site_id,
+      site_id: editForm.value.site_id || null,
       level: editForm.value.level,
       percent: editForm.value.percent,
       last_verified_at: editForm.value.last_verified_at,