refactor: cleanup and minor improvements

- Remove unused useDarkMode hook (now using shadcn theme-provider)
- Clean up MCP components (remove redundant code)
- Add restart API to settings
- Minor type improvements

package.json

@@ -57,7 +57,6 @@
     "i18next": "^25.5.2",
     "jsonc-parser": "^3.2.1",
     "lucide-react": "^0.542.0",
-    "next-themes": "^0.4.6",
     "react": "^18.2.0",
     "react-dom": "^18.2.0",
     "react-hook-form": "^7.65.0",