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

@@ -51,8 +51,8 @@
       "repo": "https://github.com/shadcn-ui/ui.git",
       "ref": "main",
       "adapter": "claude-skill",
-      "commit": "093a538453d3455159fb12a9cc897e39826f9522",
-      "syncedAt": "2026-07-08T16:00:01Z"
+      "commit": "21e4ceb94418096e21a7f1990027741a8f9b085d",
+      "syncedAt": "2026-07-09T15:59:59Z"
     },
     {
       "id": "frontend-slides",
@@ -87,8 +87,8 @@
       "repo": "https://github.com/hugohe3/ppt-master.git",
       "ref": "main",
       "adapter": "claude-skill",
-      "commit": "37427f940014c7d1aa122a3faf9cc16d64d573b6",
-      "syncedAt": "2026-07-08T16:00:01Z"
+      "commit": "b0beba5b659c664bdbf0c07227fbdee313698dd7",
+      "syncedAt": "2026-07-09T15:59:59Z"
     },
     {
       "id": "next-skills",
@@ -96,8 +96,8 @@
       "repo": "https://github.com/vercel/next.js.git",
       "ref": "canary",
       "adapter": "skill-collection",
-      "commit": "3c0fd70fc04a9bf26e7c510df9a1b7d393ac65c4",
-      "syncedAt": "2026-07-08T16:00:01Z"
+      "commit": "34d92a50266d2b70be5ac8ac147bd270f52d4a12",
+      "syncedAt": "2026-07-09T15:59:59Z"
     }
   ]
 }