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.json

@@ -553,6 +553,72 @@
         }
       ]
     },
+    {
+      "id": "grill-me",
+      "repo": "https://github.com/mattpocock/skills.git",
+      "ref": "main",
+      "adapter": "skill-collection",
+      "pluginName": "grill-me",
+      "category": "Productivity",
+      "skillsPath": "skills/productivity",
+      "includeSkills": [
+        "grill-me",
+        "grilling"
+      ],
+      "sparseCheckout": [
+        "skills/productivity/grill-me",
+        "skills/productivity/grilling",
+        "LICENSE"
+      ],
+      "brandColor": "#DC2626",
+      "metadata": {
+        "version": "0.1.0",
+        "description": "通过持续追问和分轮决策树访谈，帮助用户检验并澄清计划、设计、决策或想法。",
+        "displayName": "Grill Me",
+        "author": {
+          "name": "Matt Pocock",
+          "url": "https://github.com/mattpocock"
+        },
+        "homepage": "https://github.com/mattpocock/skills/tree/main/skills/productivity/grill-me",
+        "repository": "https://github.com/mattpocock/skills",
+        "license": "MIT",
+        "keywords": [
+          "grill-me",
+          "grilling",
+          "interview",
+          "planning",
+          "decision-making"
+        ]
+      },
+      "manifestOverrides": {
+        "interface": {
+          "displayName": "Grill Me",
+          "shortDescription": "用分轮追问检验并澄清计划、设计和决策。",
+          "longDescription": "Grill Me 通过 grilling 基础 skill 构建设计树，按决策依赖分轮提出问题和推荐答案，持续检验计划、设计、决策或想法，直到双方确认没有未说明的假设。插件同时包含 grill-me 和其必需依赖 grilling。",
+          "developerName": "Matt Pocock",
+          "category": "Productivity",
+          "capabilities": [
+            "Interactive",
+            "Read"
+          ],
+          "defaultPrompt": [
+            "使用 Grill Me 帮我彻底检验这个想法。",
+            "使用 Grill Me 通过分轮提问帮我澄清这个计划。"
+          ],
+          "websiteURL": "https://github.com/mattpocock/skills/tree/main/skills/productivity/grill-me",
+          "privacyPolicyURL": "https://github.com/mattpocock/skills",
+          "termsOfServiceURL": "https://github.com/mattpocock/skills",
+          "brandColor": "#DC2626"
+        }
+      },
+      "skillDescriptions": {
+        "grill-me": "在用户明确要求严格追问、压力测试或彻底澄清计划、设计、决策或想法时使用。",
+        "grilling": "在用户希望通过分轮问题压力测试计划、决策或想法，或使用 grill 相关触发语时使用。"
+      },
+      "includeRootFiles": [
+        "LICENSE"
+      ]
+    },
     {
       "id": "next-skills",
       "repo": "https://github.com/vercel/next.js.git",