fix: AgendaSection opinions 필드 제거 및 DB 마이그레이션 스크립트 추가

- AgendaSection 도메인 및 Entity에서 opinions 필드 제거
- ParticipantOpinion 내부 클래스 삭제
- MeetingAiController 및 AgendaSectionResponse에서 opinions 관련 로직 제거
- agenda_sections 테이블 마이그레이션 SQL 스크립트 추가
  * agenda_number: varchar(50) → integer 변환
  * decisions, pending_items, todos: text → json 변환
  * opinions 컬럼 삭제
- 자동 백업 및 롤백 기능 포함

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

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

meeting/src/main/java/com/unicorn/hgzero/meeting/infra/controller/MeetingAiController.java

@@ -162,16 +162,6 @@ public class MeetingAiController {
     }
 
     private AgendaSectionResponse.AgendaSectionItem convertToAgendaSectionItem(AgendaSection section) {
-        List<AgendaSectionResponse.AgendaSectionItem.ParticipantOpinion> opinions = null;
-        if (section.getOpinions() != null) {
-            opinions = section.getOpinions().stream()
-                    .map(op -> AgendaSectionResponse.AgendaSectionItem.ParticipantOpinion.builder()
-                            .speaker(op.getSpeaker())
-                            .opinion(op.getOpinion())
-                            .build())
-                    .collect(Collectors.toList());
-        }
-
         List<AgendaSectionResponse.AgendaSectionItem.TodoItem> todos = null;
         if (section.getTodos() != null) {
             todos = section.getTodos().stream()
@@ -194,7 +184,6 @@ public class MeetingAiController {
                 .discussions(section.getDiscussions())
                 .decisions(section.getDecisions())
                 .pendingItems(section.getPendingItems())
-                .opinions(opinions)
                 .todos(todos)
                 .createdAt(section.getCreatedAt())
                 .updatedAt(section.getUpdatedAt())

meeting/src/main/java/com/unicorn/hgzero/meeting/infra/dto/response/AgendaSectionResponse.java

@@ -58,9 +58,6 @@ public class AgendaSectionResponse {
         @Schema(description = "보류 사항 목록")
         private List<String> pendingItems;
 
-        @Schema(description = "참석자별 의견")
-        private List<ParticipantOpinion> opinions;
-
         @Schema(description = "AI 추출 Todo 목록")
         private List<TodoItem> todos;
 
@@ -72,20 +69,6 @@ public class AgendaSectionResponse {
         @JsonFormat(pattern = "yyyy-MM-dd'T'HH:mm:ss")
         private LocalDateTime updatedAt;
 
-        @Getter
-        @Builder
-        @NoArgsConstructor
-        @AllArgsConstructor
-        @Schema(description = "참석자 의견")
-        public static class ParticipantOpinion {
-
-            @Schema(description = "발언자 이름", example = "김민준")
-            private String speaker;
-
-            @Schema(description = "의견 내용", example = "타겟 고객층을 명확히 설정하여 마케팅 전략 수립 필요")
-            private String opinion;
-        }
-
         @Getter
         @Builder
         @NoArgsConstructor