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

@@ -42,8 +42,8 @@
       "repo": "https://github.com/vercel-labs/skills.git",
       "ref": "main",
       "adapter": "claude-skill",
-      "commit": "533c7df02f9b4d913fb8eba553aa99d86103d1d4",
-      "syncedAt": "2026-10-27T07:55:04Z"
+      "commit": "d8eca76d5dbe47df2d146d036e32534b74ece57a",
+      "syncedAt": "2026-10-28T01:57:49Z"
     },
     {
       "id": "generate-agents-md",
@@ -141,8 +141,8 @@
       "repo": "https://github.com/shadcn-ui/ui.git",
       "ref": "main",
       "adapter": "claude-skill",
-      "commit": "8f04138777c1b6996e709993362a7b0a12888ecf",
-      "syncedAt": "2026-10-26T16:00:00Z"
+      "commit": "96da9cc7f1aa10580a3741664e2a77c721206c00",
+      "syncedAt": "2026-10-28T01:57:49Z"
     },
     {
       "id": "frontend-slides",
@@ -177,8 +177,8 @@
       "repo": "https://github.com/hugohe3/ppt-master.git",
       "ref": "main",
       "adapter": "claude-skill",
-      "commit": "78759bf62e9a1ef43e926ff9e50afa4cfe9a63cb",
-      "syncedAt": "2026-10-24T16:00:00Z"
+      "commit": "f3660bfcd20bc07c29260b7e330261a01a2b5a6d",
+      "syncedAt": "2026-10-28T01:57:49Z"
     },
     {
       "id": "grill-me",
@@ -258,8 +258,8 @@
       "repo": "https://github.com/vercel/next.js.git",
       "ref": "canary",
       "adapter": "skill-collection",
-      "commit": "5988244ce7247f5112f00beb8050860330d93ca0",
-      "syncedAt": "2026-10-27T07:55:04Z"
+      "commit": "7356b0bcb5f22371c15dcb413afe5fb28412f52d",
+      "syncedAt": "2026-10-28T01:57:49Z"
     },
     {
       "id": "shuorenhua",