Fix marketplace.json source field format

Use URL object format instead of bare "." which fails schema validation.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude-plugin/marketplace.json

@@ -9,7 +9,11 @@
     {
       "name": "tea",
       "description": "Full operability with the tea CLI for Gitea — manage issues, PRs, releases, branches, notifications, and more from the command line.",
-      "source": ".",
+      "source": {
+        "source": "url",
+        "url": "https://gittea.kammenstraatha.duckdns.org/admin/tea-skill.git",
+        "ref": "master"
+      },
       "category": "development",
       "homepage": "https://gittea.kammenstraatha.duckdns.org/admin/tea-skill"
     }