P0-1/P0-2/P1-1: dimensions form + E2E tests + PDF export

P0-1 Backend: dimensions column on template entity + validation
P0-1 Frontend: dimensions edit UI in TemplateManager
P0-2: routeAfterGrading unit tests (10 cases), service spec fix + certificate tests, jest-e2e.json
P1-1: proper PDF generation with embedded CJK font via pdf-lib low-level API

server/src/assessment/entities/assessment-template.entity.ts

@@ -63,6 +63,9 @@ export class AssessmentTemplate {
   @JoinColumn({ name: 'knowledge_group_id' })
   knowledgeGroup: KnowledgeGroup;
 
+  @Column({ type: 'simple-json', name: 'dimensions', nullable: true })
+  dimensions: Array<{ name: string; label: string; weight: number }>;
+
   @Column({ type: 'boolean', name: 'is_active', default: true })
   isActive: boolean;