test(chromecast): [PKG-CAST-01] freeze published contracts and provenance

refactor/tasks.json

@@ -2992,11 +2992,16 @@
       "dependsOn": [
         "BASE-05"
       ],
-      "status": "todo",
+      "status": "done",
       "risk": "H",
       "deliverable": "url/sdk/icon/mimeType、loader、会话、全局 SDK 与结果",
       "acceptance": "源码/声明/README/demo/发布包差异已登记；公开形状和版本范围冻结",
-      "evidence": []
+      "evidence": [
+        "baselines/chromecast-release.json",
+        "baselines/chromecast-contract.md",
+        "baselines/chromecast-contract-validation.json",
+        "changes/2026-09-13-PKG-CAST-01-contracts.md"
+      ]
     },
     {
       "id": "PKG-CAST-02",