style: 后台管理表单对话框统一采用标签在上、输入组件在下的布局

src/view/admin/CategoryManageView.vue

@@ -124,7 +124,7 @@ onMounted(fetchData)
     </el-card>
 
     <el-dialog v-model="dialogVisible" :title="dialogTitle" width="480px" draggable>
-      <el-form ref="formRef" :model="categoryForm" :rules="formRules" label-width="90px">
+      <el-form ref="formRef" :model="categoryForm" :rules="formRules" label-position="top">
         <el-form-item label="分类名称" prop="categoryName">
           <el-input v-model="categoryForm.categoryName" placeholder="请输入分类名称" />
         </el-form-item>

src/view/admin/ContestManageView.vue

@@ -468,7 +468,7 @@ onMounted(fetchData)
 
     <!-- 新增/编辑比赛 -->
     <el-dialog v-model="dialogVisible" :title="dialogTitle" width="560px" draggable>
-      <el-form ref="formRef" :model="contestForm" :rules="formRules" label-width="100px">
+      <el-form ref="formRef" :model="contestForm" :rules="formRules" label-position="top">
         <el-form-item label="标题" prop="title">
           <el-input v-model="contestForm.title" placeholder="请输入比赛标题" />
         </el-form-item>

src/view/admin/ProblemManageView.vue

@@ -633,7 +633,7 @@ onMounted(() => {
 
     <!-- 样例编辑 -->
     <el-dialog v-model="caseDialogVisible" :title="caseForm.id ? '编辑样例' : '新增样例'" width="700px" draggable>
-      <el-form ref="caseFormRef" :model="caseForm" :rules="caseRules" label-width="80px">
+      <el-form ref="caseFormRef" :model="caseForm" :rules="caseRules" label-position="top">
         <el-form-item label="序号">
           <el-input-number v-model="caseForm.sortOrder" :min="1" />
         </el-form-item>
@@ -657,7 +657,7 @@ onMounted(() => {
 
     <!-- 评测用例编辑 -->
     <el-dialog v-model="testDialogVisible" :title="testForm.id ? '编辑评测用例' : '新增评测用例'" width="560px" draggable>
-      <el-form ref="testFormRef" :model="testForm" :rules="testRules" label-width="80px">
+      <el-form ref="testFormRef" :model="testForm" :rules="testRules" label-position="top">
         <el-form-item label="序号">
           <el-input-number v-model="testForm.sortOrder" :min="1" />
         </el-form-item>

src/view/admin/UserManageView.vue

@@ -363,7 +363,7 @@ fetchData()
 
     <!-- 新增/编辑弹窗 -->
     <el-dialog v-model="dialogVisible" :title="dialogTitle" width="500px" draggable @closed="handleDialogClosed">
-      <el-form ref="formRef" :model="userForm" :rules="formRules" label-width="80px">
+      <el-form ref="formRef" :model="userForm" :rules="formRules" label-position="top">
         <el-form-item label="用户名" prop="username">
           <el-input v-model="userForm.username" placeholder="请输入用户名" />
         </el-form-item>