Backfill the merge and cleanup records in the archived U3 card

Why: The close automation filled the card header (PR #345) but the
merge-record and cleanup-record lines still described the in-progress
state.

Evidence: CI ci/test green on the PR head (one 405 race resynced);
Backend #149 at 6abf112; task-finish recycled the worktree at ca20279
on 2026-10-11.

Impact: Archived task-card text only.

Refs: PR #345; PR #347

.task/archive/feature-generative-ui-u3.md

@@ -84,8 +84,8 @@
 
 ## 合入与清理
 
-- 合入记录：进行中——发布 PR #345；Backend #149 已合入（6abf112）；CI 于 PR HEAD 为权威验收，合入 SHA 待回填。
-- 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 #345（2026-10-11；CI ci/test 于 PR HEAD 通过，期间并行会话合入 main 引起一次 405，task-sync 后合入）。Backend #149=6abf112。真实模型回放为本地 SELF 证据（≈¥0.08，M3），CI 为 GATE。
+- 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 ca20279）；可再生构建产物显式清除；卡片闭合经 PR #347。
 
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