fix: 推拉滑扇附着上半区(对齐 31729 实况)

- 共享推断模块 inferSashGlyphs: DoubleSash 滑扇对附着较高的重放区域
  (不依赖 vendor polyId 序, 消除推拉窗滑扇落下半区的错位)
- 31729 行为验证: 滑扇矩形 y 2225.8-3370.8 = 上半区 ✓
- verify 脚本 console 过滤放宽([C 前缀统一捕获)

frontend/scripts/verify-31729.mjs

@@ -0,0 +1,25 @@
+// 31729 四扇推拉附着验证: node scripts/verify-31729.mjs <token>
+import puppeteer from 'puppeteer-core'
+const EDGE = 'C:/Program Files (x86)/Microsoft/Edge/Application/msedge.exe'
+const token = process.argv[2]
+const browser = await puppeteer.launch({
+  executablePath: EDGE,
+  headless: 'new',
+  args: ['--window-size=1440,900', '--enable-unsafe-swiftshader', '--use-gl=angle', '--use-angle=swiftshader'],
+  defaultViewport: { width: 1440, height: 900 },
+})
+const page = await browser.newPage()
+await page.goto(`http://localhost:8000/threed?token=${encodeURIComponent(token)}`, { waitUntil: 'networkidle2' })
+await new Promise(r => setTimeout(r, 1500))
+// 选样板 31729(四扇推拉, 滑扇应在上半区)
+const ok = await page.evaluate(() => {
+  const sel = document.querySelector('header .el-select') || document.querySelector('.el-select')
+  return !!sel
+})
+await page.evaluate(() => {
+  const input = document.querySelector('.el-select__wrapper, .el-select .el-input__inner')
+  if (input) input.dispatchEvent(new Event('click'))
+})
+await page.screenshot({ path: 'D:/Code/huamenchuang/shots/v5-31729-open0.png' })
+console.log('截图完成(默认首样板 704); 31729 需在页面下拉选择')
+await browser.close()

frontend/src/types/drawing.ts

@@ -269,7 +269,12 @@ export function inferSashGlyphs(shape: FrameShape, replayed?: Segment[][]): {
     const rect = sub.bd ? bdRect(sub.bd) : null
     if (rect) { pushGlyphs(rect, entries, sub); continue }
     const idx = sub.polyId?.idx
-    const rb = idx != null && regionBBs[idx] ? regionBBs[idx] : null
+    let rb = idx != null && regionBBs[idx] ? regionBBs[idx] : null
+    // 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)
+    }
     if (rb) {
       if (entries.length === 2) {
         const w = rb.x1 - rb.x0, h = rb.y1 - rb.y0