fix skill-creator install: use anthropics/skills marketplace

skill-creator is bundled in the "example-skills" plugin from
anthropics/skills repo, not in anthropics/claude-code marketplace.
Adds anthropic-agent-skills marketplace and installs example-skills.

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

install-plugins.sh

@@ -342,8 +342,13 @@ install_plugin() {
 # These are NOT in claude-plugins-official — they require the claude-code marketplace
 info "Adding Anthropic bundled plugins marketplace..."
 claude plugin marketplace add anthropics/claude-code 2>/dev/null || true
+
+info "Adding Anthropic skills marketplace..."
+claude plugin marketplace add anthropics/skills 2>/dev/null || true
 install_plugin "security-guidance"  "claude-code-plugins"
-install_plugin "skill-creator"  "claude-code-plugins"
+# skill-creator is in "example-skills" plugin from anthropics/skills marketplace
+# (not in claude-code marketplace — it's a separate repo)
+install_plugin "example-skills"     "anthropic-agent-skills"
 # install_plugin "frontend-design"    "claude-code-plugins"
 install_plugin "pr-review-toolkit"  "claude-code-plugins"
 install_plugin "plugin-dev"         "claude-code-plugins"

settings.json

@@ -233,6 +233,15 @@
         "source": "github",
         "repo": "nextlevelbuilder/ui-ux-pro-max-skill"
       }
+    },
+    "anthropic-agent-skills": {
+      "source": {
+        "source": "github",
+        "repo": "anthropics/skills"
+      }
     }
+  },
+  "enabledPlugins": {
+    "example-skills@anthropic-agent-skills": true
   }
 }