chore(builds): 重編 tier2 成品 manifest——repo_dirty:true 修正為乾淨 HEAD（94d5452）

出貨 D87（Arcrun#119）到 stage 時卡在 build-bundles.mjs 的落後閘：main 上現有的
.worker-builds/manifest.json 記著 repo_head=8286c8a（4b6cc15 那個 commit 的父提交）
且 repo_dirty:true——是那次 commit 在完成前先跑了建置腳本，manifest 跟著沒完成的
工作樹一起被 commit 進去。

在乾淨的 main HEAD（94d5452）重跑 scripts/build-worker-artifacts.mjs：五顆
worker 內容位元組完全相同（cypher-executor sha256 8e6487478bc8... 不變，
證明前一份的實際內容其實是對的，只是 metadata 記錯），這次只更新
generated_at／repo_head／repo_dirty／source_commit 四個欄位為正確值。

.worker-builds/manifest.json

@@ -1,14 +1,14 @@
 {
   "schema": 1,
   "built_for": "arcrun-tier2-worker-artifacts",
-  "generated_at": "2026-08-14T04:50:51.373Z",
-  "repo_head": "8286c8afec1b225fcec21654cfd1cad3143231fe",
-  "repo_dirty": true,
+  "generated_at": "2026-08-14T05:27:06.148Z",
+  "repo_head": "94d5452425893ea9f2ed0b7166c7a87ca8866cec",
+  "repo_dirty": false,
   "workers": [
     {
       "name": "arcrun-cypher-executor",
       "source_dir": "cypher-executor",
-      "source_commit": "8286c8afec1b225fcec21654cfd1cad3143231fe",
+      "source_commit": "4b6cc159b8b264ddca27da86922b2d4847ba0871",
       "main_module": "worker.mjs",
       "main_file": "arcrun-cypher-executor/worker.mjs",
       "js_bytes": 589935,