feat: v2.9 拖拽移动模式(右键菜单入口)

- 菜单新增'拖拽移动此单元': 进入后鼠标移动即拖动单元(增量平移)
- 点击画布落下并 emit change, 菜单动作与拖拽移动并列
- 配套验证脚本 verify-move.mjs(真实鼠标序列端到端)

frontend/src/components/CombineCanvas.vue

@@ -11,6 +11,7 @@
     <transition name="fade">
       <div v-if="ctxMenu.visible" class="ctx-menu" :style="{ left: ctxMenu.x + 'px', top: ctxMenu.y + 'px' }">
         <div class="ctx-title">单元 #{{ ctxMenu.uid }}</div>
+        <div class="ctx-item" data-action="drag-move"><el-icon><Rank /></el-icon>拖拽移动此单元</div>
         <div class="ctx-item" data-action="rotate-cw"><el-icon><RefreshRight /></el-icon>顺时针旋转 90°</div>
         <div class="ctx-item" data-action="rotate-ccw"><el-icon><RefreshLeft /></el-icon>逆时针旋转 90°</div>
         <div class="ctx-item" data-action="mirror"><el-icon><Switch /></el-icon>水平镜像</div>
@@ -290,6 +291,15 @@ function hitUnit(p: Pt): number | null {
 function onDown(e: MouseEvent) {
   closeMenu()
   const rect = cvRef.value!.getBoundingClientRect()
+  // 拖拽移动模式: 点击落下
+  if (moveModeUid.value !== null) {
+    moveModeUid.value = null
+    moveLast = null
+    hint.value = '已落下'
+    render()
+    emit('change')
+    return
+  }
   const p = toModel(e.clientX - rect.left, e.clientY - rect.top)
   const uid = hitUnit(p)
   if (props.editable && uid !== null) {
@@ -307,8 +317,18 @@ function onDown(e: MouseEvent) {
 }
 
 function onMove(e: MouseEvent) {
+  const rect = cvRef.value!.getBoundingClientRect()
+  // 拖拽移动模式: 鼠标移动即拖动单元
+  if (moveModeUid.value !== null) {
+    const p = toModel(e.clientX - rect.left, e.clientY - rect.top)
+    if (moveLast) {
+      translateUid(moveModeUid.value, p.x - moveLast.x, p.y - moveLast.y)
+      moveLast = p
+      render()
+    }
+    return
+  }
   if (dragUnit) {
-    const rect = cvRef.value!.getBoundingClientRect()
     const p = toModel(e.clientX - rect.left, e.clientY - rect.top)
     const bb = unitBBox(dragUnit.uid)
     if (!bb) return
@@ -382,10 +402,22 @@ function ctxAction(a: string) {
   const uid = ctxMenu.uid
   closeMenu()
   if (uid === null) return
+  // 拖拽移动模式: 后续鼠标移动拖动该单元, 点击落下; Esc 取消还原
+  if (a === 'drag-move') {
+    moveModeUid.value = uid
+    moveOriginBb = unitBBox(uid)
+    moveLast = null
+    hint.value = '拖拽移动模式：移动鼠标拖动单元，点击落下；Esc 取消'
+    return
+  }
   // 动作统一 emit 给父组件执行（父组件持有 canvasRef 与 shapes 权威状态）
   emit('ctx', a, uid)
 }
 
+const moveModeUid = ref<number | null>(null)
+let moveLast: Pt | null = null
+let moveOriginBb: BBox | null = null
+
 function refresh() { render() }
 
 /** 选中单元缩放到目标尺寸（几何按比例缩放，锚定自身左下角） */
@@ -469,6 +501,21 @@ defineExpose({ refresh, modelAt, exportDrawing, rotateUnit, mirrorUnit, resizeSe
 onMounted(() => {
   watch(() => props.shapes, () => { selectedUid.value = null; closeMenu(); rebuild() }, { immediate: true })
   window.addEventListener('resize', render)
+  // Esc 取消拖拽移动(还原到模式进入时的位置)
+  const onKey = (e: KeyboardEvent) => {
+    if (e.key === 'Escape' && moveModeUid.value !== null) {
+      const bb = unitBBox(moveModeUid.value)
+      if (bb && moveOriginBb) {
+        translateUid(moveModeUid.value,
+          (moveOriginBb.x0 + moveOriginBb.x1) / 2 - (bb.x0 + bb.x1) / 2,
+          (moveOriginBb.y0 + moveOriginBb.y1) / 2 - (bb.y0 + bb.y1) / 2)
+      }
+      moveModeUid.value = null
+      render()
+    }
+  }
+  window.addEventListener('keydown', onKey)
+  onBeforeUnmount(() => window.removeEventListener('keydown', onKey))
   // 点击菜单外关闭 + 菜单项动作（在 mousedown 阶段触发，真实点击必有效）
   document.addEventListener('mousedown', (e: MouseEvent) => {
     const item = (e.target as HTMLElement).closest?.('.ctx-item')