chore: fork from IRIS track 供 LICA 部门独立运行

- 复制来源: /home/yueli/track @ 192c8ee (feature/ai-audit-update)
- 组织隔离目标: LICA
- 端口规划: 前端 8030 / 后端 8031 / 数据库 8032
- 已排除 deploy.sh、deploy_full.sh、docker-compose.prod.yml（IRIS 生产发布脚本）
- 已排除工作区未提交改动，取干净的 192c8ee 状态

backend/app/models/notification.py

@@ -0,0 +1,53 @@
+"""通知模型 — 任务转交/驳回等事件的消息提醒"""
+import uuid
+from datetime import datetime
+from sqlalchemy import String, DateTime, Boolean, ForeignKey, Text
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.models.base import Base
+from app.core.time_utils import get_beijing_time
+
+# 通知类型常量
+NOTIFY_TRANSFER = "TRANSFER"   # 新任务派发/转交
+NOTIFY_REJECT = "REJECT"       # 品质驳回
+NOTIFY_COMMENT = "COMMENT"     # 留言提醒
+
+
+class Notification(Base):
+    __tablename__ = "notifications"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4,
+    )
+
+    user_id: Mapped[str] = mapped_column(
+        String(64), nullable=False, index=True, comment="接收人ID（逻辑外键→老系统）",
+    )
+
+    title: Mapped[str] = mapped_column(
+        String(200), nullable=False, comment="通知标题",
+    )
+
+    content: Mapped[str] = mapped_column(
+        Text, nullable=False, comment="通知内容详情",
+    )
+
+    type: Mapped[str] = mapped_column(
+        String(20), nullable=False, comment="通知类型: TRANSFER(转交派发) | REJECT(驳回)",
+    )
+
+    task_id: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True), ForeignKey("tasks.id", ondelete="SET NULL"), nullable=True, comment="关联任务ID",
+    )
+
+    is_read: Mapped[bool] = mapped_column(
+        Boolean, default=False, comment="是否已读",
+    )
+
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), default=get_beijing_time, comment="创建时间",
+    )
+
+    def __repr__(self) -> str:
+        return f"<Notification {self.type} → {self.user_id}>"