refactor: remove obsolete scaffolding and dead modules

Drop the unused root hello-world controller, empty CommonModule imports, development seeding code, legacy student report entity, stale DTOs, notification hook, and their placeholder tests.

apps/server/src/entities/index.ts

@@ -32,5 +32,4 @@ export { ExamScore } from './exam-score.entity';
 export { LearningRecord } from './learning-record.entity';
 export { ResultArchive } from './result-archive.entity';
 export { ArchiveAttachment } from './archive-attachment.entity';
-export { StudentReport } from './student-report.entity';
 export { StudentDingMapping } from './student-ding-mapping.entity';

apps/server/src/entities/student-report.entity.ts

@@ -1,42 +0,0 @@
-import {
-  Entity,
-  PrimaryGeneratedColumn,
-  Column,
-  CreateDateColumn,
-  UpdateDateColumn,
-  ManyToOne,
-  JoinColumn,
-} from 'typeorm';
-import { Student } from './student.entity';
-
-@Entity('student_reports')
-export class StudentReport {
-  @PrimaryGeneratedColumn()
-  id: number;
-
-  @Column({ name: 'student_id', type: 'integer' })
-  studentId: number;
-
-  @ManyToOne(() => Student, { eager: true })
-  @JoinColumn({ name: 'student_id' })
-  student: Student;
-
-  @Column({ name: 'snapshot_data', type: 'simple-json', nullable: true })
-  snapshotData: Record<string, unknown>;
-
-  @Column({ name: 'html_content', type: 'text', nullable: true })
-  htmlContent: string;
-
-  @Column({ name: 'pdf_path', length: 500, nullable: true })
-  pdfPath: string;
-
-  @Column({ name: 'generated_at', type: 'datetime', nullable: true })
-  generatedAt: Date;
-
-
-  @CreateDateColumn({ name: 'created_at' })
-  createdAt: Date;
-
-  @UpdateDateColumn({ name: 'updated_at' })
-  updatedAt: Date;
-}