feat: v1.6 组合画布编辑能力增强

- 选中单元可视化: 蓝色虚线框+四角手柄+实时尺寸标注
- 精确尺寸编辑: 工具栏 W/H 输入框(几何按比例缩放, 锚定左下角)
- 方向键微调: 1mm/Shift+方向键 10mm
- 右侧单元清单点击选中与画布联动, selSize 双向同步

frontend/src/components/CombineCanvas.vue

@@ -218,6 +218,27 @@ function render() {
   for (const h of guides.h) { ctx.beginPath(); ctx.moveTo(0, ty(h)); ctx.lineTo(W, ty(h)); ctx.stroke() }
   ctx.setLineDash([])
 
+  // 选中单元: 蓝色虚线框 + 角点手柄 + 尺寸标注
+  if (selectedUid.value !== null) {
+    const bb = unitBBox(selectedUid.value)
+    if (bb) {
+      const x0 = tx(bb.x0), x1 = tx(bb.x1), y0 = ty(bb.y1), y1 = ty(bb.y0)
+      ctx.strokeStyle = '#409eff'
+      ctx.setLineDash([6, 4])
+      ctx.lineWidth = 1.5
+      ctx.strokeRect(x0 - 4, y0 - 4, (x1 - x0) + 8, (y1 - y0) + 8)
+      ctx.setLineDash([])
+      ctx.fillStyle = '#409eff'
+      for (const [hx, hy] of [[x0, y0], [x1, y0], [x0, y1], [x1, y1]]) {
+        ctx.fillRect(hx - 4, hy - 4, 8, 8)
+      }
+      ctx.font = 'bold 12px sans-serif'
+      ctx.textAlign = 'center'
+      ctx.fillText(`${Math.round(bb.x1 - bb.x0)} × ${Math.round(bb.y1 - bb.y0)} mm`, (x0 + x1) / 2, y0 - 10)
+      ctx.textAlign = 'left'
+    }
+  }
+
   hint.value = `${uids().length} 个单元 · 总尺寸 ${Math.round(gw)} × ${Math.round(gh)} mm`
 }
 
@@ -308,6 +329,37 @@ function modelAt(clientX: number, clientY: number): Pt {
 }
 
 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） */
+function resizeSelected(newW: number, newH: number) {
+  if (selectedUid.value === null) return
+  const target = props.shapes.filter(s => s.__uid === selectedUid.value)
+  const bb = bbOfLocal(target)
+  if (!bb) return
+  const w = bb.x1 - bb.x0, h = bb.y1 - bb.y0
+  if (w < 10 || h < 10) return
+  const sx = Math.max(0.05, newW / w), sy = Math.max(0.05, newH / h)
+  const scX = (p: any) => { p.x = bb.x0 + (p.x - bb.x0) * sx }
+  const scY = (p: any) => { p.y = bb.y0 + (p.y - bb.y0) * sy }
+  for (const s of target) {
+    for (const r of (s.polygon?.polygon ?? [])) {
+      for (const seg of r) { scX(seg.ps); scY(seg.ps); scX(seg.pe); scY(seg.pe) }
+    }
+    for (const sp of (s.mm?.sp ?? [])) { scX(sp.line.pt); scY(sp.line.pt) }
+    for (const sub of (s.sm ?? [])) if (sub.bd) { scX(sub.bd.from); scY(sub.bd.from); scX(sub.bd.to); scY(sub.bd.to) }
+  }
+  refresh()
+  emit('change')
+}
+
+/** 方向键微调（mm） */
+function nudgeSelected(dx: number, dy: number) {
+  if (selectedUid.value === null) return
+  translateUid(selectedUid.value, dx, dy)
+  refresh()
+  emit('change')
+}
+
 function exportDrawing(): string | null {
   if (!props.shapes.length) return null
   return JSON.stringify({
@@ -315,7 +367,7 @@ function exportDrawing(): string | null {
     epi: [], sbf: [], wlc: '', wall: [], scale: 0, note: [],
   })
 }
-defineExpose({ refresh, modelAt, exportDrawing, rotateUnit, mirrorUnit })
+defineExpose({ refresh, modelAt, exportDrawing, rotateUnit, mirrorUnit, resizeSelected, nudgeSelected })
 
 onMounted(() => {
   watch(() => props.shapes, () => { selectedUid.value = null; rebuild() }, { immediate: true })