feat(linkage): 鞍座改为预备生产位 + 在线改人工触发 + 计划删除

- 上卷鞍座=预备生产位（不生产）；投入生产后离开鞍座、进入生产中并转入物料跟踪，鞍座随即空出
- 在线状态改为人工触发：移动到入口端才变在线，引擎不再自动上线(ensure_online 置空)
- 单卷在产：投入生产时若已有在产卷则拒绝
- 物料跟踪显示在产卷实时进度(客户端外推带头长度/进度条)
- 入口跟踪鞍座卡片改为预备生产展示(去掉进度)
- 计划管理新增删除按钮 + DELETE /plan/{id}(生产中不可删)

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

backend/app/services/line_service.py

@@ -51,9 +51,9 @@ async def place_at_position(db: AsyncSession, plan: ProductionPlan, position: st
     plan.run_speed = 0
     plan.run_length_m = 0
     plan.position = position
-    if plan.status == "producing":
+    # 移动到入口端即变「在线」（人工触发，非自动）
+    if plan.status != "produced":
         plan.status = "online"
-    await ensure_online(db)
 
 
 def _shift_of(dt: datetime) -> str:
@@ -66,70 +66,40 @@ async def _saddle_plan(db: AsyncSession):
 
 
 async def ensure_online(db: AsyncSession):
-    """单卷在产：有卷在上卷鞍座/生产中时不保留在线队首；否则把最早 ready 置为唯一在线。"""
-    res = await db.execute(
-        select(ProductionPlan).where(ProductionPlan.status == "online", ProductionPlan.on_saddle != 1)
-    )
-    online = list(res.scalars())
-
-    # 是否已有在产/在鞍座的卷
-    res2 = await db.execute(
-        select(ProductionPlan).where(
-            (ProductionPlan.status == "producing") | (ProductionPlan.on_saddle == 1)
-        )
-    )
-    active = res2.scalars().first() is not None
-
-    if active:
-        # 正在生产时，不再保留「在线」队首，全部回退 ready，等当前卷完成
-        for p in online:
-            p.status = "ready"
-        return
-
-    if len(online) > 1:
-        online.sort(key=lambda p: (p.plan_date or datetime.max, p.id))
-        for p in online[1:]:
-            p.status = "ready"
-        online = online[:1]
-    if not online:
-        res = await db.execute(
-            select(ProductionPlan)
-            .where(ProductionPlan.status == "ready")
-            .order_by(asc(ProductionPlan.plan_date), asc(ProductionPlan.id))
-            .limit(1)
-        )
-        head = res.scalar_one_or_none()
-        if head:
-            head.status = "online"
+    """在线为人工触发：用户手动「移动到入口」才变在线，引擎不再自动上线。"""
+    return
 
 
 async def move_to_saddle(db: AsyncSession, plan: ProductionPlan):
-    """把计划移动到上卷鞍座：上卷即获得速度 → 生产中。"""
+    """把计划移动到上卷鞍座（预备生产位，尚未生产）。"""
     occupied = await _saddle_plan(db)
     if occupied and occupied.id != plan.id:
-        raise ValueError("上卷鞍座已被占用，请等待当前钢卷生产完成")
-    now = datetime.now()
+        raise ValueError("上卷鞍座已有预备卷，请先投入生产或移走")
     plan.on_saddle = 1
     plan.position = SADDLE_NAME
-    plan.saddle_at = now
+    plan.saddle_at = datetime.now()
+    plan.run_started_at = None
+    plan.run_speed = 0
+    plan.run_length_m = 0
     if plan.status != "produced":
-        plan.run_started_at = now
-        plan.run_speed = SIM_SPEED_M_MIN
-        plan.run_length_m = 0
-        plan.status = "producing"
+        plan.status = "online"   # 在鞍座预备（待投入生产）
     await ensure_online(db)
 
 
 async def commit_plan(db: AsyncSession, plan: ProductionPlan):
-    """投入生产（兜底）：鞍座计划置为生产中。"""
-    if plan.on_saddle != 1:
-        await move_to_saddle(db, plan)
-        return
-    if plan.run_started_at is None:
-        plan.run_started_at = datetime.now()
+    """投入生产：鞍座预备卷进入生产中，离开鞍座进入产线（物料跟踪）。"""
+    res = await db.execute(select(ProductionPlan).where(ProductionPlan.status == "producing"))
+    if res.scalars().first() is not None:
+        raise ValueError("产线已有钢卷在生产，请等待当前卷完成")
+    now = datetime.now()
+    plan.on_saddle = 0          # 离开上卷鞍座
+    plan.position = None
+    plan.saddle_at = None
+    plan.run_started_at = now
     plan.run_speed = SIM_SPEED_M_MIN
+    plan.run_length_m = 0
     plan.status = "producing"
-    await ensure_online(db)
+    await ensure_online(db)     # 鞍座空出 → 队首自动上线
 
 
 async def _produce(db: AsyncSession, plan: ProductionPlan):
@@ -183,17 +153,17 @@ async def _produce(db: AsyncSession, plan: ProductionPlan):
     logger.info(f"生产完成并产生实绩: {plan.cold_coil_no or plan.plan_no}")
 
 
-async def advance_saddle(db: AsyncSession):
-    """推进鞍座计划：累计带头长度到 2000m → 生产完成。"""
-    plan = await _saddle_plan(db)
-    if not plan:
+async def advance_production(db: AsyncSession):
+    """推进产线在产卷（已离开鞍座）：累计带头长度到 2000m → 生产完成。"""
+    res = await db.execute(select(ProductionPlan).where(ProductionPlan.status == "producing"))
+    plan = res.scalars().first()
+    if not plan or not plan.run_started_at:
         return
     now = datetime.now()
-    if plan.status == "producing" and plan.run_started_at:
-        elapsed = (now - plan.run_started_at).total_seconds()
-        plan.run_length_m = min(TARGET_LENGTH_M, (plan.run_speed or 0) / 60.0 * elapsed)
-        if plan.run_length_m >= TARGET_LENGTH_M:
-            await _produce(db, plan)
+    elapsed = (now - plan.run_started_at).total_seconds()
+    plan.run_length_m = min(TARGET_LENGTH_M, (plan.run_speed or 0) / 60.0 * elapsed)
+    if plan.run_length_m >= TARGET_LENGTH_M:
+        await _produce(db, plan)
 
 
 async def _get_line_state(db: AsyncSession) -> LineState:
@@ -243,9 +213,8 @@ async def detect_downtime(db: AsyncSession):
 
 
 async def tick(db: AsyncSession):
-    """引擎单步：上线 + 推进鞍座 + 停机检测。"""
-    await ensure_online(db)
-    await advance_saddle(db)
+    """引擎单步：推进在产卷 + 停机检测（在线为人工触发，不自动上线）。"""
+    await advance_production(db)
     await detect_downtime(db)