feat: add flutter plugin as a github source (#6)

Author: jorgecoca

.claude-plugin/marketplace.json

@@ -14,8 +14,11 @@
       "name": "very-good-ai-flutter-plugin",
       "description": "Claude Code plugin to enhance and accelerate Flutter & Dart development, built by Very Good Ventures",
       "version": "0.0.1",
-      "source": "github",
-      "repo": "VeryGoodOpenSource/very_good_ai_flutter_plugin",
+      "source": {
+        "source": "github",
+        "repo": "VeryGoodOpenSource/very_good_ai_flutter_plugin"
+      },
+      "repository": "https://github.com/VeryGoodOpenSource/very_good_ai_flutter_plugin",
       "homepage": "https://github.com/VeryGoodOpenSource/very_good_ai_flutter_plugin",
       "author": {
         "name": "Very Good Ventures",