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/message.py

@@ -0,0 +1,33 @@
+"""产品协同留言板模型"""
+import uuid
+from datetime import datetime
+from sqlalchemy import String, Text, DateTime, ForeignKey
+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
+
+
+class ProductMessage(Base):
+    __tablename__ = "product_messages"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4,
+    )
+    product_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("products.id", ondelete="CASCADE"),
+        index=True,
+        nullable=False,
+        comment="所属产品 ID",
+    )
+    operator_id: Mapped[str] = mapped_column(
+        String(50), nullable=False, comment="留言人姓名或工号",
+    )
+    content: Mapped[str] = mapped_column(
+        Text, nullable=False, comment="留言内容",
+    )
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), default=get_beijing_time, comment="留言时间（北京时间）",
+    )