feat(linkage): 计划-鞍座-实绩-停机联动 + 成本管理页

后端：
- 计划录入即「准备好」，队首(最早)自动「在线」(唯一)
- 新增上卷鞍座联动引擎 line_service：移动→鞍座→(有速度/投入生产)→生产中
  →带头达2000m→生产完成并自动产生实绩、持久化运行数据
- 停机自动检测：线速度为0持续>10min 自动新增待补充停机记录，恢复后自动结束
- /plan/start=移动到鞍座, 新增 /plan/{id}/commit 投入生产, /plan/saddle/current,
  /plan/seed 批量插入(轧制力模式)；后台引擎循环自动推进
- 新增成本管理：CostRecord 模型 + /cost CRUD + 9 类成本项(乳化液/盐酸/碱/电/水/蒸汽…)

前端：
- 入口跟踪重构为单个上卷鞍座工位(实时速度/带头长度进度/投入生产)+待上卷卡片+队列，
  计划列表/卡片/队列均可「移动」
- 新增成本管理页(成本项切换 + 柱+线图 + 明细表 + 时间筛选 + 新增)，布局参考乳化液耗量统计

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/app/models/__init__.py

@@ -9,6 +9,8 @@ from app.models.pdi import PDIRecord
 from app.models.quality import QcTask, QcTaskItem, QcDefect
 from app.models.energy import EnergyRecord
 from app.models.inspection import EqpChecklist, EqpChecklistItem, EqpInspectionRecord, EqpInspectionDetail
+from app.models.line_state import LineState
+from app.models.cost import CostRecord
 
 __all__ = [
     "User",
@@ -22,4 +24,5 @@ __all__ = [
     "QcTask", "QcTaskItem", "QcDefect",
     "EnergyRecord",
     "EqpChecklist", "EqpChecklistItem", "EqpInspectionRecord", "EqpInspectionDetail",
+    "LineState", "CostRecord",
 ]

backend/app/models/cost.py

@@ -0,0 +1,20 @@
+from sqlalchemy import Column, Integer, String, Float, DateTime, Text, func
+from app.database import Base
+
+
+class CostRecord(Base):
+    """成本/消耗记录（乳化液、盐酸、电、水、蒸汽等）"""
+    __tablename__ = "cost_records"
+
+    id = Column(Integer, primary_key=True, index=True)
+    item = Column(String(30), index=True, nullable=False, comment="成本项编码")
+    item_name = Column(String(50), comment="成本项名称")
+    unit = Column(String(20), comment="计量单位")
+    record_date = Column(DateTime, nullable=False, index=True, comment="记录时间")
+    shift_a = Column(Float, default=0, comment="A班量")
+    shift_b = Column(Float, default=0, comment="B班量")
+    unit_cost = Column(Float, default=0, comment="吨耗量")
+    remark = Column(Text, comment="备注")
+    created_by = Column(String(50))
+    created_at = Column(DateTime, server_default=func.now())
+    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now())

backend/app/models/line_state.py

@@ -0,0 +1,13 @@
+from sqlalchemy import Column, Integer, Float, DateTime, func
+from app.database import Base
+
+
+class LineState(Base):
+    """产线运行状态单例（id=1），用于停机自动检测。"""
+    __tablename__ = "line_state"
+
+    id = Column(Integer, primary_key=True, index=True)
+    speed = Column(Float, default=0, comment="当前线速度 m/min")
+    zero_since = Column(DateTime, comment="速度为0的起始时间")
+    open_downtime_id = Column(Integer, comment="当前未结束的自动停机记录id")
+    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now())

backend/app/models/plan.py

@@ -35,6 +35,14 @@ class ProductionPlan(Base):
     incoming_od = Column(Float, comment="来料外径 mm")
     split_weights = Column(JSON, comment="分卷重量 [t,...]")
 
+    # 上卷鞍座 / 生产联动
+    on_saddle = Column(Integer, default=0, comment="是否在上卷鞍座 0/1")
+    saddle_at = Column(DateTime, comment="移动到鞍座时间")
+    run_started_at = Column(DateTime, comment="投入生产(有速度)时间")
+    run_speed = Column(Float, default=0, comment="当前线速度 m/min")
+    run_length_m = Column(Float, default=0, comment="带头已生产长度 m")
+    produced_at = Column(DateTime, comment="生产完成时间")
+
     # 兼容历史字段
     shift = Column(String(10), comment="班次")
     plan_quantity = Column(Integer, default=0)