Add artifact plugin

Adds a skill for creating interactive HTML artifacts — self-contained
single-file explorers with visual controls, live preview, and prompt
output with copy button.

Includes templates for:
- Design playgrounds (components, layouts, spacing, color, typography)
- Data explorers (SQL, APIs, pipelines, regex)
- Concept maps (learning, exploration, relationships)
- Writing tools (tone, structure, audience)

plugins/artifact/.claude-plugin/plugin.json

@@ -0,0 +1,8 @@
+{
+  "name": "artifact",
+  "description": "Creates interactive HTML artifacts — self-contained single-file explorers with visual controls, live preview, and prompt output with copy button",
+  "author": {
+    "name": "Anthropic",
+    "email": "support@anthropic.com"
+  }
+}