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/JuliusBrussee/caveman.git",
       "ref": "main",
       "adapter": "codex-plugin",
-      "commit": "367fdb7f0f8f8e7994b5aab632c7ce5014802b32",
-      "syncedAt": "2026-09-04T16:00:00Z"
+      "commit": "5184b3d11ac6a1acb7d44b9bfaa31698157cff97",
+      "syncedAt": "2026-09-05T16:00:00Z"
     },
     {
       "id": "taste-skill",
@@ -96,8 +96,8 @@
       "repo": "https://github.com/hugohe3/ppt-master.git",
       "ref": "main",
       "adapter": "claude-skill",
-      "commit": "8295ca1416ad17cf25ed17765024bc7ba411782c",
-      "syncedAt": "2026-09-04T16:00:00Z"
+      "commit": "d3d81fe3cf4cc642de225159586308bbe98eeb4d",
+      "syncedAt": "2026-09-05T16:00:00Z"
     },
     {
       "id": "grill-me",
@@ -132,8 +132,8 @@
       "repo": "https://github.com/vercel/next.js.git",
       "ref": "canary",
       "adapter": "skill-collection",
-      "commit": "602a2aba900e45fb2edd694f463f435430678e1f",
-      "syncedAt": "2026-09-04T16:00:00Z"
+      "commit": "6685283fe8533a469ee1a9455e2bc4047c7453cb",
+      "syncedAt": "2026-09-05T16:00:00Z"
     },
     {
       "id": "shuorenhua",