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

@@ -96,8 +96,8 @@
       "repo": "https://github.com/hugohe3/ppt-master.git",
       "ref": "main",
       "adapter": "claude-skill",
-      "commit": "ebd74d1f1d61a686f0f80e10abde5029fc4beeca",
-      "syncedAt": "2026-08-25T16:00:00Z"
+      "commit": "d6bcaf96b7946667f4a8871b0688b903181db527",
+      "syncedAt": "2026-08-28T16:00:00Z"
     },
     {
       "id": "grill-me",
@@ -114,8 +114,8 @@
       "repo": "https://github.com/vercel/next.js.git",
       "ref": "canary",
       "adapter": "skill-collection",
-      "commit": "0a2bd1d531595b1d6d115c2c912f897e9053d3b8",
-      "syncedAt": "2026-08-27T16:00:00Z"
+      "commit": "1cb20a1d1431f9216f44230a1e5a698c23ba9f70",
+      "syncedAt": "2026-08-28T16:00:00Z"
     }
   ]
 }