Close 1 merged task card(s) and archive them

Why: branches merged into main had left their task cards open; backfill status and archive to prevent bookkeeping debt.
Evidence: feature-agent-s0-workspace-overlay.md(PR#318) — merges verified via git log --merges against origin/main.
Impact: .task/*.md moved to .task/archive/ with status backfilled; no code or submodule change.
Refs: task.sh close (card-autoclose-r1)

.task/archive/feature-agent-s0-workspace-overlay.md

@@ -1,6 +1,6 @@
 # feature/agent-s0-workspace-overlay 任务卡
 
-任务主记录：PR #318 https://git-home.u1680832.nyat.app:30319/weichen/Agent-System-Dev/pulls/318；状态：进行中（待合入）；owner：weichen
+任务主记录：PR #318 https://git-home.u1680832.nyat.app:30319/weichen/Agent-System-Dev/pulls/318；状态：已完成（回填）；owner：weichen
 
 ## 基线与授权
 
@@ -210,3 +210,9 @@
 }
 ```
 | 同步前验收 | 73c901fa341a3653d6e0826d0da3497507995482 | b332b2e9ee22690de76cb82fa54e74b3442d1dd0 | 2026-10-11T02:24:03Z |
+
+## 闭合记录（card-autoclose 回填）
+
+- 依据：merge 92ca774e94966c13a7e036baae9455f152f4b59c（PR #318）已包含于 origin/main，分支成果已落盘；本段为合入后回填。
+- 合并主题：Merge pull request 'S0 first shape: task workspace overlay with frozen base and CAS apply (pin bd4b3bc)' (#318) from feature/agent-s0-workspace-overlay into main
+- 归档：随闭合移入 .task/archive/；任务执行期的过程证据见原任务记录与 PR。