feat(core-edu): v2 P3.14 考试实时事件 + pino 修复

新增 3 RPC：ExtendExam/ForceSubmitExam/ReorderExamQuestions

新增 3 Kafka 事件：exam.extended/exam.force_submitted/exam.question_reordered

exams.service.ts 新增 3 方法 + Outbox 事务内写入 + TOPIC_MAP 映射

grpc.server.ts 注册 3 handler + grpc-smoke 测试

logger.ts pino 导入修复（import pino → import { pino }）

27/27 smoke test 通过

services/core-edu/src/shared/outbox/outbox.publisher.ts

@@ -17,6 +17,10 @@ const TOPIC_MAP: Record<string, string> = {
   "exam.submitted": "edu.teaching.exam.submitted",
   "exam.graded": "edu.teaching.exam.graded",
   "exam.deleted": "edu.teaching.exam.deleted",
+  // Exam realtime events (P3.14: 供 msg → push-gateway → student-portal WebSocket)
+  "exam.extended": "edu.teaching.exam.extended",
+  "exam.force_submitted": "edu.teaching.exam.force_submitted",
+  "exam.question_reordered": "edu.teaching.exam.question_reordered",
   // Homework events
   "homework.assigned": "edu.teaching.homework.assigned",
   "homework.submitted": "edu.teaching.homework.submitted",