refactor: 완료 반려 필드 분리 및 데이터 구조 개선

- backend: completion_rejection_reason 등 전용 필드 추가
- 기존 management_comment에 섞여있던 완료 반려 내용 분리
- 현황판: 완료 반려 내역 별도 카드로 표시
- 관리함: 해결방안에 완료 반려 내용 제외하여 표시
- DB 마이그레이션: completion_rejected_at, completion_rejected_by_id, completion_rejection_reason 필드 추가

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

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

backend/database/models.py

@@ -143,7 +143,12 @@ class Issue(Base):
     completion_requested_by_id = Column(Integer, ForeignKey("users.id"))  # 완료 신청자
     completion_photo_path = Column(String(500))  # 완료 사진 경로
     completion_comment = Column(Text)  # 완료 코멘트
-    
+
+    # 완료 반려 관련 필드들
+    completion_rejected_at = Column(DateTime)  # 완료 반려 시간
+    completion_rejected_by_id = Column(Integer, ForeignKey("users.id"))  # 완료 반려자
+    completion_rejection_reason = Column(Text)  # 완료 반려 사유
+
     # Relationships
     reporter = relationship("User", back_populates="issues", foreign_keys=[reporter_id])
     reviewer = relationship("User", foreign_keys=[reviewed_by_id], overlaps="reviewed_issues")
@@ -183,14 +188,28 @@ class DailyWork(Base):
 
 class ProjectDailyWork(Base):
     __tablename__ = "project_daily_works"
-    
+
     id = Column(Integer, primary_key=True, index=True)
     date = Column(DateTime, nullable=False, index=True)
     project_id = Column(BigInteger, ForeignKey("projects.id"), nullable=False)
     hours = Column(Float, nullable=False)
     created_by_id = Column(Integer, ForeignKey("users.id"))
     created_at = Column(DateTime, default=get_kst_now)
-    
+
     # Relationships
     project = relationship("Project")
     created_by = relationship("User")
+
+class DeletionLog(Base):
+    __tablename__ = "deletion_logs"
+
+    id = Column(Integer, primary_key=True, index=True)
+    entity_type = Column(String(50), nullable=False)  # 'issue', 'project', 'daily_work' 등
+    entity_id = Column(Integer, nullable=False)  # 삭제된 엔티티의 ID
+    entity_data = Column(JSONB, nullable=False)  # 삭제된 데이터 전체 (JSON)
+    deleted_by_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    deleted_at = Column(DateTime, default=get_kst_now, nullable=False)
+    reason = Column(Text)  # 삭제 사유 (선택사항)
+
+    # Relationships
+    deleted_by = relationship("User")

backend/database/schemas.py

@@ -152,7 +152,12 @@ class Issue(IssueBase):
     completion_requested_by_id: Optional[int] = None  # 완료 신청자
     completion_photo_path: Optional[str] = None  # 완료 사진 경로
     completion_comment: Optional[str] = None  # 완료 코멘트
-    
+
+    # 완료 반려 관련 필드들
+    completion_rejected_at: Optional[datetime] = None  # 완료 반려 시간
+    completion_rejected_by_id: Optional[int] = None  # 완료 반려자
+    completion_rejection_reason: Optional[str] = None  # 완료 반려 사유
+
     class Config:
         from_attributes = True
 
@@ -200,6 +205,10 @@ class CompletionRequestRequest(BaseModel):
     completion_photo: str  # 완료 사진 (Base64)
     completion_comment: Optional[str] = None  # 완료 코멘트
 
+class CompletionRejectionRequest(BaseModel):
+    """완료 신청 반려 요청"""
+    rejection_reason: str  # 반려 사유
+
 class ManagementUpdateRequest(BaseModel):
     """관리함에서 이슈 업데이트 요청"""
     final_description: Optional[str] = None