feat: P2-12 Teacher profile/workspace + P2-13 Multi-class comparison

P2-12 Teacher Management:
- Add profile JSON field (subjects, joinedAt, qualifications) to User entity
- Add GET/PUT /rbac/users/:id/profile endpoints with UpdateProfileDto
- Add GET /rbac/teacher-workspace endpoint returning assignedClasses,
  todaySchedules, and myStudents
- Create /teacher-workspace page with tabs (My Classes, Today's Schedule,
  My Students)
- Add route with PermissionRoute and menu item in MainLayout

P2-13 Student Archive Multi-class:
- Add GET /students/:id/compare-classes endpoint returning side-by-side
  enrollment data with per-class attendance statistics
- Students module now includes ClassStudent and AttendanceRecord entities
- No 2-enrollment cap existed in the codebase; student enrollments
  already return all records via class-student table

apps/server/src/students/students.controller.ts

@@ -280,4 +280,10 @@ export class StudentsController {
     });
     return result;
   }
+
+  @Get(':id/compare-classes')
+  @RequirePermission('student:view')
+  compareClasses(@Param('id') id: string) {
+    return this.service.compareClasses(+id);
+  }
 }

apps/server/src/students/students.module.ts

@@ -1,11 +1,13 @@
 import { Module } from '@nestjs/common';
 import { TypeOrmModule } from '@nestjs/typeorm';
 import { Student } from '../entities/student.entity';
+import { ClassStudent } from '../entities/class-student.entity';
+import { AttendanceRecord } from '../entities/attendance-record.entity';
 import { StudentsService } from './students.service';
 import { StudentsController } from './students.controller';
 
 @Module({
-  imports: [TypeOrmModule.forFeature([Student])],
+  imports: [TypeOrmModule.forFeature([Student, ClassStudent, AttendanceRecord])],
   controllers: [StudentsController],
   providers: [StudentsService],
   exports: [StudentsService],

apps/server/src/students/students.service.ts

@@ -2,11 +2,18 @@ import { Injectable, NotFoundException, BadRequestException } from '@nestjs/comm
 import { InjectRepository } from '@nestjs/typeorm';
 import { Repository, Like, Not, In } from 'typeorm';
 import { Student } from '../entities/student.entity';
+import { ClassStudent } from '../entities/class-student.entity';
+import { AttendanceRecord } from '../entities/attendance-record.entity';
 import { CreateStudentDto, UpdateStudentDto } from './dto/student.dto';
 
 @Injectable()
 export class StudentsService {
-  constructor(@InjectRepository(Student) private repo: Repository<Student>) {}
+
+  constructor(
+    @InjectRepository(Student) private repo: Repository<Student>,
+    @InjectRepository(ClassStudent) private classStudentRepo: Repository<ClassStudent>,
+    @InjectRepository(AttendanceRecord) private attendanceRepo: Repository<AttendanceRecord>,
+  ) {}
 
   async findAll(query?: { name?: string; status?: string; includeArchived?: boolean }) {
     const where: any = {};
@@ -129,4 +136,61 @@ export class StudentsService {
       skipped,
     };
   }
+
+  async compareClasses(studentId: number) {
+    const student = await this.repo.findOne({ where: { id: studentId } });
+    if (!student) throw new NotFoundException('学生不存在');
+
+    // Get all class enrollments for this student
+    const enrollments = await this.classStudentRepo.find({
+      where: { studentId },
+      relations: ['class'],
+    });
+
+    if (enrollments.length === 0) {
+      return { student, enrollments: [] };
+    }
+
+    // For each enrollment, compute attendance stats
+    const classIds = enrollments.map((e) => e.classId);
+    const attendanceRecords = await this.attendanceRepo.find({
+      where: { studentId, classId: In(classIds) },
+    });
+
+    // Group attendance by class
+    const attendanceByClass = new Map<number, AttendanceRecord[]>();
+    for (const r of attendanceRecords) {
+      const list = attendanceByClass.get(r.classId!) || [];
+      list.push(r);
+      attendanceByClass.set(r.classId!, list);
+    }
+
+    const comparison = enrollments.map((e) => {
+      const records = attendanceByClass.get(e.classId) || [];
+      const total = records.length;
+      const present = records.filter((r) => r.status === 'present' || r.status === '正常').length;
+      const absent = records.filter((r) => r.status === 'absent' || r.status === '缺勤').length;
+      const late = records.filter((r) => r.status === 'late' || r.status === '迟到').length;
+      const leave = records.filter((r) => r.status === 'leave' || r.status === '请假').length;
+
+      return {
+        classId: e.classId,
+        className: e.class?.name || '',
+        classType: e.class?.classType || '',
+        joinDate: e.joinDate,
+        leaveDate: e.leaveDate,
+        status: e.status,
+        attendanceStats: {
+          total,
+          present,
+          absent,
+          late,
+          leave,
+          rate: total > 0 ? Math.round((present / total) * 100) : 0,
+        },
+      };
+    });
+
+    return { student, enrollments: comparison };
+  }
 }