refactor: move plugin manifest to repository root per Claude Code best practices

- Move plugin.json from skills/unraid/.claude-plugin/ to .claude-plugin/
- Update validation script to use correct plugin manifest path
- Add plugin structure section to root README.md
- Add installation instructions to skills/unraid/README.md
- Aligns with Claude Code's expectation for source: './' in marketplace.json

skills/unraid/.claude-plugin/plugin.json

@@ -1,27 +0,0 @@
-{
-  "name": "unraid",
-  "description": "Query and monitor Unraid servers via GraphQL API - array status, disk health, containers, VMs, system monitoring",
-  "version": "0.2.0",
-  "author": {
-    "name": "jmagar",
-    "email": "jmagar@users.noreply.github.com"
-  },
-  "homepage": "https://github.com/jmagar/unraid-mcp",
-  "repository": "https://github.com/jmagar/unraid-mcp",
-  "mcpServers": {
-    "unraid": {
-      "command": "uv",
-      "args": [
-        "run",
-        "--directory",
-        "${CLAUDE_PLUGIN_ROOT}",
-        "unraid-mcp-server"
-      ],
-      "env": {
-        "UNRAID_API_URL": "${UNRAID_API_URL}",
-        "UNRAID_API_KEY": "${UNRAID_API_KEY}",
-        "UNRAID_MCP_TRANSPORT": "stdio"
-      }
-    }
-  }
-}

skills/unraid/README.md

@@ -23,6 +23,17 @@ skills/unraid/
     └── quick-reference.md            # Common queries cheat sheet
 ```
 
+## Installation
+
+This skill is part of the Unraid MCP plugin. Install via the Claude Code marketplace:
+
+```bash
+/plugin marketplace add jmagar/unraid-mcp
+/plugin install unraid @unraid-mcp
+```
+
+The plugin includes both the MCP server and this skill at `skills/unraid/`.
+
 ## Quick Start
 
 1. **Set your credentials:**