Backfill the merge and cleanup records in the archived U4 card

Why: The close automation filled the card header (PR #351) but the
merge-record and cleanup-record lines still described the in-progress
state.

Evidence: CI ci/test green on the retriggered head (first run failed
on runner network glitch and a hung test job, both infra); component
chain Core #27/#28, UI #42-#45, Frontend #53, Backend #150; task-finish
recycled the worktree at b877edd on 2026-10-11.

Impact: Archived task-card text only.

Refs: PR #351; PR #356

.task/archive/feature-generative-ui-u4.md

@@ -83,8 +83,8 @@
 
 ## 合入与清理
 
-- 合入记录：进行中——发布 PR #351；组件链 Core #27/#28、UI #42/#43/#44/#45、Frontend #53、Backend #150 已合入；CI 于 PR HEAD 为权威验收。
-- 清理记录：NOT_RUN（授权依据、写者退出确认、worktree/分支/任务卡处置）
+- 合入记录：已合入——PR #351（2026-10-11；首个 CI run 因 runner 网络毛刺失败【test-pg 检出连不上 127.0.0.1:3000】且 test 作业挂起，空提交重触发后 CI 绿；405 竞态一次自动补同步）。组件链：Core #27=7e98a7e前→#28 合并 89f3906、UI #42/#43/#44/#45=ef6d9e7、Frontend #53=68f6c86、Backend #150（core 依赖钉）。CI 为 GATE；组件套件与本地组合 make test 为 SELF 佐证。
+- 清理记录：已完成——TASK_WRITERS_STOPPED=1 make task-finish 于 2026-10-11 回收 worktree 与本地/远端任务分支（observed_head b877edd）；可再生构建产物显式清除；卡片闭合经 PR #356。
 
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