Record rewind verification on the task card

Why: The card still said combined verification was pending after make test, make build, and the mock rewind check.
Evidence: Dialog listed notes.txt to restore and note.txt to skip; confirm removed notes.txt and appended the system note.
Impact: Reviewers see the browser check on the same card that becomes the PR body.
Refs: feature/durable-rewind
Co-authored-by: Cursor <cursoragent@cursor.com>

.task/feature-durable-rewind.md

@@ -22,5 +22,5 @@
 ## 结果与验证（完成后填写）
 
 - 结果：native fb2b3b7，squad a3b49e7，core 5dc190e，backend bead033，frontend e26119d，ui 8e66bce。
-- 验证：各仓单测已过。组合验证见后续 make test。
+- 验证：各仓单测已过。worktree 内 `make test` 与 `make build` 通过。临时 mock（127.0.0.1:8802）上打开回滚确认：无检查点时显示「没有需要回滚的文件」且确认按钮不可用；写入检查点后列出将恢复的 notes.txt 与跳过的 note.txt，确认后 notes.txt 被删除、note.txt 保持外部内容，并追加系统提示。
 - 影响与剩余项：回退链默认空；检查点只追踪显式写入；shell 与 python 的改动不回滚。