refactor: move MCP server config inline to plugin.json

Move MCP server configuration from standalone .mcp.json to inline
definition in plugin.json. This consolidates all plugin metadata
in a single location.

- Add type: stdio and env fields to inline config
- Remove redundant .mcp.json file
- Maintains same functionality with cleaner structure

.claude-plugin/plugin.json

@@ -10,13 +10,17 @@
   "repository": "https://github.com/jmagar/unraid-mcp",
   "mcpServers": {
     "unraid": {
+      "type": "stdio",
       "command": "uv",
       "args": [
         "run",
         "--directory",
         "${CLAUDE_PLUGIN_ROOT}",
         "unraid-mcp-server"
-      ]
+      ],
+      "env": {
+        "UNRAID_MCP_TRANSPORT": "stdio"
+      }
     }
   }
 }

.mcp.json

@@ -1,12 +0,0 @@
-{
-  "mcpServers": {
-    "unraid": {
-      "type": "stdio",
-      "command": "uv",
-      "args": ["run", "--directory", "${CLAUDE_PLUGIN_ROOT}", "unraid-mcp-server"],
-      "env": {
-        "UNRAID_MCP_TRANSPORT": "stdio"
-      }
-    }
-  }
-}