test(auto-thumbnail): [PKG-AUTO-THUMB-02] reproduce extraction and lifecycle failures

refactor/tasks.json

@@ -1755,11 +1755,15 @@
         "ENG-03",
         "ENG-05"
       ],
-      "status": "todo",
+      "status": "done",
       "risk": "H",
       "deliverable": "抽帧边界、短视频、失败、连续来源和销毁中的抽帧",
       "acceptance": "旧版本行为可重跑，成功/失败/切源/销毁有必要断言",
-      "evidence": []
+      "evidence": [
+        "baselines/auto-thumbnail-failures.md",
+        "baselines/auto-thumbnail-failures-validation.json",
+        "changes/2026-09-13-PKG-AUTO-THUMB-02-failures.md"
+      ]
     },
     {
       "id": "PKG-AUTO-THUMB-03",