fix(embed): watchdog also clears hover + releases capture (third freeze layer — capture suspends pointerleave, lost release never frees it)

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

apps/viewer/src/pages/embed/EmbedStream.vue

@@ -235,8 +235,22 @@ function onPointerDown(event: PointerEvent): void {
   pointerWatchdog = setTimeout(() => {
     pointerWatchdog = null;
     pointerDownY = null;
+    // 统一清指针族原因（滚动卡死第三层修复 2026-09-23）：pointer capture 挂起
+    // 期间 pointerleave 不派发，而窗外释放使 up 永不送达 iframe → capture 不
+    // 释放 → hover 原因同样永久卡住。看门狗兜底：释放捕获 + 清
+    // pointer/manual/hover 三因（窗内正常路径由各事件自行清理，不受影响）。
+    try {
+      const el = viewportEl.value;
+      if (el !== null && el.hasPointerCapture(event.pointerId)) {
+        el.releasePointerCapture(event.pointerId);
+      }
+    } catch {
+      /* 指针已不在：忽略 */
+    }
+    hoverPointerIsMouse = false;
     setReason('pointer', false);
     setReason('manual', false);
+    setReason('hover', false);
     scheduleResume();
   }, POINTER_WATCHDOG_MS);
 }