feat(ms-ai-architect): re-sync vendored design-system, source_commit now true [skip-docs]

DS-repo restored scripts/sync-design-system.mjs with an explicit source
allowlist and verified the command; ran their exact command (never one
reconstructed locally). MANIFEST.json was rewritten by the script itself,
never edited by hand.

source_commit now reads efaa3d0 (playground-design-system's main on the
public mirror), verified reachable via git ls-remote against the public
remote and git cat-file -t locally — in contrast to the previous c1b7bad,
which does not exist as a git object in that repo at all. 26/27 files
byte-identical to the source; only their README.md content differs.

Replaced the three stale prose points in README.md and docs/playground.md
that described the missing command and the untrustworthy source_commit.

Suite: 1070/1070 (tracked kb-update + kb-eval test files).

[skip-docs]: README.md and docs/playground.md are the doc update this task
required (vendoring section accuracy). CLAUDE.md's command/agent/skill
surface is unaffected — no new commands, agents, or skills.

playground/vendor/playground-design-system/MANIFEST.json

@@ -1,13 +1,13 @@
 {
   "generated_by": "scripts/sync-design-system.mjs",
   "do_not_edit": true,
-  "source": "shared/playground-design-system/",
-  "source_commit": "c1b7bad3899c5cfe9ff90663003609b018aa79a0",
-  "sync_date": "2026-05-15T14:11:07.444Z",
+  "source": "playground-design-system",
+  "source_commit": "efaa3d0e79f1b06976735831e5bf8cab42f7e6a9",
+  "sync_date": "2026-08-27T08:37:47.101Z",
   "file_count": 27,
   "files": {
     "CHANGELOG.md": "b5018b46cd0830334109e915d23b5554c060412c2b7e132f97f2933e5dd5d79c",
-    "README.md": "83de0e29b207c979b7b2a3327b7a4ec0c2e1b4d3705ee2677f26c28c3a3ee643",
+    "README.md": "8d8e86251f0c5a5d2f29e91d3b5a1fd2b40d7a79e4791ade237c10112ce9ce3c",
     "base.css": "df0db874473412eb771b7355b589f7478042987756898f0921584286bd5ba70a",
     "components-tier2.css": "c2cb7e9d76d6af28d50db654030413777feb2f2f2b93213e598de8b686b14523",
     "components-tier3-supplement.css": "51fab10377d80029d6552613069d46fd14ce66af77fe6705b1c6bdf5c9e6481e",