fix: code review — 7 issues resolved

(C1) Add dimensionScores/radarData/passed columns to AssessmentSession
(C2) Mock DataSource in service.spec.ts + app.e2e-spec.ts
(C3) Mock AuditLogService in controller.spec.ts
(C4) Rewrite deleteSession tests for dataSource.transaction
(I1) batchDeleteSessions uses transaction with certificate cleanup
(I2) extractDimensionScores reads from session property
(I3/I5) PDF generator supports multi-page + newline splitting
(I4) findOne inside transaction uses deleteCondition

server/test/app.e2e-spec.ts

@@ -1,5 +1,6 @@
 import { Test, TestingModule } from '@nestjs/testing';
 import { getRepositoryToken } from '@nestjs/typeorm';
+import { DataSource } from 'typeorm';
 import { AssessmentService } from '../src/assessment/assessment.service';
 import { AssessmentSession } from '../src/assessment/entities/assessment-session.entity';
 import { AssessmentQuestion } from '../src/assessment/entities/assessment-question.entity';
@@ -20,6 +21,16 @@ import { ChatService } from '../src/chat/chat.service';
 import { I18nService } from '../src/i18n/i18n.service';
 import { TenantService } from '../src/tenant/tenant.service';
 
+const mockManager = () => ({
+  findOne: jest.fn(),
+  delete: jest.fn().mockResolvedValue({ affected: 1 }),
+  save: jest.fn(),
+});
+
+const mockDataSource = () => ({
+  transaction: jest.fn(async (cb: any) => cb(mockManager())),
+});
+
 /**
  * Certificate integration tests — verify the full certificate lifecycle
  * through the AssessmentService with mocked repositories.
@@ -61,6 +72,7 @@ describe('Certificate (integration)', () => {
         { provide: ChatService, useFactory: mockSvc },
         { provide: I18nService, useFactory: mockSvc },
         { provide: TenantService, useFactory: mockSvc },
+        { provide: DataSource, useFactory: mockDataSource },
       ],
     }).compile();