feat: 移除PDI和订单号字段，新增设备巡检模块

- 从物料跟踪页面移除订单号列和表单字段
- 从导航菜单移除PDI管理，添加设备巡检
- 新增InspectionLocation和InspectionRecord后端模型和API
- 新增设备巡检前端页面（左侧点位列表，右侧设备和历史记录）

backend/app/models/material.py

@@ -0,0 +1,56 @@
+from sqlalchemy import Column, Integer, String, Float, DateTime, Enum, Text, ForeignKey, func
+from sqlalchemy.orm import relationship
+from app.database import Base
+import enum
+
+
+class CoilStatus(str, enum.Enum):
+    WAITING = "waiting"       # 等待入线
+    ON_LINE = "on_line"       # 在线处理
+    FINISHED = "finished"     # 处理完成
+    ABNORMAL = "abnormal"     # 异常
+
+
+class Coil(Base):
+    """钢卷主档"""
+    __tablename__ = "coils"
+
+    id = Column(Integer, primary_key=True, index=True)
+    coil_no = Column(String(30), unique=True, nullable=False, index=True, comment="卷号")
+    order_no = Column(String(30), index=True, comment="订单号")
+    steel_grade = Column(String(30), comment="钢种")
+    spec_thickness = Column(Float, comment="规格厚度mm")
+    spec_width = Column(Float, comment="规格宽度mm")
+    target_thickness = Column(Float, comment="目标厚度mm")
+    target_width = Column(Float, comment="目标宽度mm")
+    gross_weight = Column(Float, comment="毛重kg")
+    net_weight = Column(Float, comment="净重kg")
+    inner_diameter = Column(Float, comment="内径mm")
+    status = Column(Enum(CoilStatus), default=CoilStatus.WAITING)
+    plan_id = Column(Integer, ForeignKey("production_plans.id"), nullable=True)
+    remark = Column(Text)
+    created_at = Column(DateTime, server_default=func.now())
+    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now())
+
+    tracking = relationship("MaterialTracking", back_populates="coil")
+
+
+class MaterialTracking(Base):
+    """物料跟踪记录"""
+    __tablename__ = "material_tracking"
+
+    id = Column(Integer, primary_key=True, index=True)
+    coil_id = Column(Integer, ForeignKey("coils.id"), nullable=False, index=True)
+    coil_no = Column(String(30), nullable=False, index=True)
+    position = Column(String(50), comment="当前位置/工位")
+    event_type = Column(String(30), comment="事件类型: entry/exit/process/inspect")
+    event_desc = Column(String(200), comment="事件描述")
+    actual_thickness = Column(Float, comment="实测厚度")
+    actual_width = Column(Float, comment="实测宽度")
+    speed = Column(Float, comment="线速度m/min")
+    tension = Column(Float, comment="张力N")
+    operator = Column(String(50))
+    event_time = Column(DateTime, nullable=False, index=True)
+    created_at = Column(DateTime, server_default=func.now())
+
+    coil = relationship("Coil", back_populates="tracking")