test(dpip): [PKG-DPIP-02] reproduce window races and DOM rollback failures

refactor/tasks.json

@@ -3009,11 +3009,15 @@
         "ENG-03",
         "ENG-05"
       ],
-      "status": "todo",
+      "status": "done",
       "risk": "H",
       "deliverable": "不支持/拒绝、重复打开、pagehide、核心销毁和视频 PiP fallback",
       "acceptance": "旧版本行为可重跑，成功/失败/切源/销毁有必要断言",
-      "evidence": []
+      "evidence": [
+        "changes/2026-09-12-PKG-DPIP-02-tests.md",
+        "baselines/dpip-behavior-validation.json",
+        "dpip-validation.md"
+      ]
     },
     {
       "id": "PKG-DPIP-03",