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/test/app.e2e-spec.ts

@@ -1,26 +0,0 @@
-import { Test, TestingModule } from '@nestjs/testing';
-import { INestApplication } from '@nestjs/common';
-import request from 'supertest';
-import { App } from 'supertest/types';
-import { AppModule } from './../src/app.module';
-
-describe('AppController (e2e)', () => {
-  let app: INestApplication<App>;
-
-  beforeEach(async () => {
-    const moduleFixture: TestingModule = await Test.createTestingModule({
-      imports: [AppModule],
-    }).compile();
-
-    app = moduleFixture.createNestApplication();
-    await app.init();
-  });
-
-  it('/ (GET)', () => {
-    return request(app.getHttpServer()).get('/').expect(200).expect('Hello World!');
-  });
-
-  afterEach(async () => {
-    await app.close();
-  });
-});