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.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],