Fix plugin structure for Claude Code compatibility

Move plugin.json to .claude-plugin/ directory as required by Claude Code
plugin specification. The plugin manifest must be located at
.claude-plugin/plugin.json for proper plugin discovery and loading.

Also fix author and repository URL to point to correct owner.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.claude-plugin/plugin.json

@@ -0,0 +1,12 @@
+{
+  "name": "andrej-karpathy-skills",
+  "displayName": "Karpathy Coding Guidelines",
+  "version": "1.0.0",
+  "description": "Behavioral guidelines to reduce common LLM coding mistakes, derived from Andrej Karpathy's observations on LLM coding pitfalls",
+  "author": "forrestchang",
+  "license": "MIT",
+  "repository": "https://github.com/forrestchang/andrej-karpathy-skills",
+  "skills": [
+    "skills/karpathy-guidelines/SKILL.md"
+  ]
+}