Fix: TranscriptionServiceImpl에 sessionId 파라미터 추가

- SegmentCreated.of() 메서드 호출 시 sessionId 파라미터 누락 수정
- sessionId에 meetingId 값 할당

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

stt/src/main/java/com/unicorn/hgzero/stt/service/TranscriptionServiceImpl.java

@@ -85,6 +85,7 @@ public class TranscriptionServiceImpl implements TranscriptionService {
         );
         TranscriptionEvent.SegmentCreated event = TranscriptionEvent.SegmentCreated.of(
                 segmentId, request.getRecordingId(), recording.getMeetingId(),
+                recording.getMeetingId(), // sessionId (meetingId와 동일)
                 recognizedText, speakerId, "화자-" + speakerId.substring(4),
                 timestampAsDateTime, 3.5, confidence, warningFlag
         );