Sync third-party and MCP marketplace plugins

Constraint: Public skills are published only by explicit administrator action unless they are tracked third-party market sources.
Confidence: high
Scope-risk: narrow
Directive: Keep private/internal skills out of the public marketplace and preserve normal incremental market Git history.
Tested: Marketplace validation passed.

config/external-sources.lock.json

@@ -132,8 +132,8 @@
       "repo": "https://github.com/shadcn-ui/ui.git",
       "ref": "main",
       "adapter": "claude-skill",
-      "commit": "7ff7dbf8669fa3392c294ee745dc8d8c3cee842c",
-      "syncedAt": "2026-10-06T07:26:41Z"
+      "commit": "debae9baea4d5c6bd0b1a857b09664db4b925818",
+      "syncedAt": "2026-10-06T16:00:00Z"
     },
     {
       "id": "frontend-slides",
@@ -177,8 +177,8 @@
       "repo": "https://github.com/mattpocock/skills.git",
       "ref": "main",
       "adapter": "skill-collection",
-      "commit": "4588b32ecab9ecc9fc8cc6b6c5e7d675b6004b0d",
-      "syncedAt": "2026-10-05T16:00:00Z"
+      "commit": "6fd947921b935b7e1e69293a200400f0fdd5c15f",
+      "syncedAt": "2026-10-06T16:00:00Z"
     },
     {
       "id": "updating-gitea-repositories",
@@ -258,8 +258,8 @@
       "repo": "https://github.com/vercel/next.js.git",
       "ref": "canary",
       "adapter": "skill-collection",
-      "commit": "8619c015f8cc9b26fbe10c5e97b0f8cb9ed5cb92",
-      "syncedAt": "2026-10-06T07:26:41Z"
+      "commit": "b22e5a299cb58577ce86f21b6a0f7bb31a6168f2",
+      "syncedAt": "2026-10-06T16:00:00Z"
     },
     {
       "id": "shuorenhua",