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.

plugins/codex/plugins/shadcn/THIRD_PARTY_SOURCE.json

@@ -2,8 +2,8 @@
   "sourceId": "shadcn",
   "repo": "https://github.com/shadcn-ui/ui.git",
   "ref": "main",
-  "commit": "683a5a9b370acdb7785a0529434e6a3b8c7e0441",
+  "commit": "b4a618b97e35f5dadf3a00d51f410c84a2567d4d",
   "adapter": "claude-skill",
   "sourcePath": "skills/shadcn",
-  "syncedAt": "2026-08-26T16:00:00Z"
+  "syncedAt": "2026-08-30T16:00:00Z"
 }