feat(admin): 班级花名册导入确认流程与教师候选人

- 提交体条件化：空数组不发送，修复全匹配/全新建两种场景被后端 @ArrayMinSize 拒 400
- 无论是否新建学生都先确认，避免已匹配学生被一键加入无提示
- 学员下拉保留学号/ID 兜底区分同名；科目去重键小写对齐后端唯一索引
- 任课老师空科目前端拦截；教师候选人相关调整

apps/admin/src/pages/Classes/teacher-candidate.ts

@@ -10,7 +10,6 @@ export interface TeacherCandidateUser {
   isArchived: boolean;
   studentStatus?: string | null;
   roles?: TeacherCandidateRole[];
-  profile?: { subjects?: string[] } | null;
 }
 
 const isSuperAdminRole = (role: TeacherCandidateRole) =>
@@ -31,16 +30,7 @@ export const buildTeacherCandidateLabel = (user: TeacherCandidateUser) => {
   const roleNames = [
     ...new Set((user.roles || []).flatMap((role) => (role.name ? [role.name] : []))),
   ];
-  const subjects = [
-    ...new Set(
-      (user.profile?.subjects || []).flatMap((subject) => {
-        const trimmed = subject.trim();
-        return trimmed ? [trimmed] : [];
-      }),
-    ),
-  ];
-
-  return [identity, roleNames.join('/'), subjects.join('/')].filter(Boolean).join(' · ');
+  return [identity, roleNames.join('/')].filter(Boolean).join(' · ');
 };
 
 export const buildTeacherCandidateOptions = (users: TeacherCandidateUser[]) =>