Add local settings for MCP and update command execution

- Created a new settings.local.json file to enable MCP servers with "shadcn".
- Updated .mcp.json to change the command execution from "npx" to "cmd" for better compatibility.

.claude/settings.local.json

@@ -0,0 +1,6 @@
+{
+  "enabledMcpjsonServers": [
+    "shadcn"
+  ],
+  "enableAllProjectMcpServers": true
+}