Add external plugin brainmaxxing (#2473)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

.github/plugin/marketplace.json

@@ -166,6 +166,34 @@
       "description": "Wander an endless first-person backrooms in a Copilot canvas while agents work; their status ghost-writes on the walls.",
       "version": "1.0.0"
     },
+    {
+      "name": "brainmaxxing",
+      "description": "Codebase-grounded concept-mastery quizzes with an interactive BrainMax Canvas dashboard.",
+      "version": "1.0.0",
+      "author": {
+        "name": "Julia Muiruri",
+        "url": "https://juliawakiru.dev"
+      },
+      "repository": "https://github.com/juliamuiruri4/brainmaxxing",
+      "homepage": "https://github.com/juliamuiruri4/brainmaxxing",
+      "license": "MIT",
+      "keywords": [
+        "assessment",
+        "canvas",
+        "developer-education",
+        "learning",
+        "quiz",
+        "skills-mastery",
+        "software-engineering",
+        "student-developer"
+      ],
+      "source": {
+        "source": "github",
+        "repo": "juliamuiruri4/brainmaxxing",
+        "ref": "v1.0.0",
+        "sha": "8a8a102ff3ab8736f015764207cdb7e68fcd5ecf"
+      }
+    },
     {
       "name": "cast-imaging",
       "source": "plugins/cast-imaging",

plugins/external.json

@@ -78,6 +78,34 @@
       "path": ".github/plugins/azure-skills"
     }
   },
+  {
+    "name": "brainmaxxing",
+    "description": "Codebase-grounded concept-mastery quizzes with an interactive BrainMax Canvas dashboard.",
+    "version": "1.0.0",
+    "author": {
+      "name": "Julia Muiruri",
+      "url": "https://juliawakiru.dev"
+    },
+    "repository": "https://github.com/juliamuiruri4/brainmaxxing",
+    "homepage": "https://github.com/juliamuiruri4/brainmaxxing",
+    "license": "MIT",
+    "keywords": [
+      "assessment",
+      "canvas",
+      "developer-education",
+      "learning",
+      "quiz",
+      "skills-mastery",
+      "software-engineering",
+      "student-developer"
+    ],
+    "source": {
+      "source": "github",
+      "repo": "juliamuiruri4/brainmaxxing",
+      "ref": "v1.0.0",
+      "sha": "8a8a102ff3ab8736f015764207cdb7e68fcd5ecf"
+    }
+  },
   {
     "name": "chrome-devtools-plugin",
     "description": "Reliable automation, in-depth debugging, and performance analysis in Chrome using Chrome DevTools and Puppeteer.",