feat: v2.8 3D 预览放大模式+类型修正

- 组合页 3D 预览卡片: 放大按钮切换近全屏浮层(inset 2.5vh/2.5vw)
- 默认高度 300→380, 切换后派发 resize 让 3D 自适应
- drawing.ts 滑扇附着 reduce 种子类型修正(移除未定义 BBox 引用)
- vue-tsc 零错误, 构建通过

frontend/src/types/drawing.ts

@@ -273,7 +273,7 @@ export function inferSashGlyphs(shape: FrameShape, replayed?: Segment[][]): {
     // 推拉双扇: 附着较高的区域(推拉窗滑扇在上半部, 对齐 31729 实况)
     const kind = sub.type === 'DoubleSash' ? 'sliding' : 'casement'
     if (kind === 'sliding') {
-      rb = regionBBs.reduce((p, c) => (!p || (c.y0 + c.y1) / 2 > (p.y0 + p.y1) / 2 ? c : p), null as BBox | null)
+      rb = regionBBs.reduce((p, c) => (!p || (c.y0 + c.y1) / 2 > (p.y0 + p.y1) / 2 ? c : p), regionBBs[0] ?? null)
     }
     if (rb) {
       if (entries.length === 2) {

frontend/src/views/CombineView.vue

@@ -78,7 +78,15 @@
           </div>
         </transition-group>
       </el-card>
-      <el-card header="3D 预览" style="margin-top:16px">
+      <el-card header="3D 预览" style="margin-top:16px" :class="{ 'preview-large': previewLarge }">
+        <template #header>
+          <div class="head-row">
+            <span>3D 预览</span>
+            <el-button size="small" text type="primary" @click="togglePreviewLarge">
+              <el-icon><FullScreen /></el-icon>{{ previewLarge ? '还原' : '放大' }}
+            </el-button>
+          </div>
+        </template>
         <div class="threed-box">
           <WindoorThreed v-if="shapes.length" :drawing-data="combinedJson" />
           <el-empty v-else description="—" :image-size="50" />
@@ -111,6 +119,12 @@ const selectedUid = ref<number | null>(null)
 const saveName = ref('')
 const saving = ref(false)
 const equalHeight = ref(true)
+const previewLarge = ref(false)
+
+function togglePreviewLarge() {
+  previewLarge.value = !previewLarge.value
+  setTimeout(() => window.dispatchEvent(new Event('resize')), 60)
+}
 const canvasRef = ref()
 let uidSeq = 1
 const rev = ref(0)
@@ -343,7 +357,9 @@ onBeforeUnmount(() => window.removeEventListener('keydown', onKeydown))
 .unit-info { flex: 1; min-width: 0; }
 .unit-name { font-size: 13px; color: #303133; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
 .unit-size { font-size: 11px; color: #909399; }
-.threed-box { height: 300px; }
+.threed-box { height: 380px; }
+.preview-large { position: fixed; inset: 2.5vh 2.5vw; z-index: 2001; margin: 0 !important; }
+.preview-large .threed-box { height: calc(100% - 40px); }
 .list-enter-active, .list-leave-active { transition: all .2s; }
 .list-enter-from, .list-leave-to { opacity: 0; transform: translateX(12px); }
 </style>