Describe the bug

The Desktop app's extension command parser doesn't respect quotes when parsing commands with spaces. The splitCmdAndArgs() function uses .split(/\s+/) which splits on all whitespace, breaking paths like /Applications/IntelliJ IDEA.app/... even when quoted.

To Reproduce

1. Go to Settings → Extensions
2. Click "Add Extension"
3. Enter command: "/Applications/IntelliJ IDEA.app/Contents/jbr/Contents/Home/bin/java" -classpath "/path/with spaces/lib.jar" com.example.Main
4. Save the extension
5. Check ~/.config/goose/config.yaml - the command is incorrectly split with quotes appearing in wrong places

Expected behavior

Quoted strings should be preserved as single arguments, similar to shell behavior. The CLI already uses shlex::split for this - the Desktop UI should use equivalent parsing (e.g., shell-quote npm package).

Screenshots

N/A

Please provide the following information

• OS & Arch: macOS
• Interface: UI
• Version: v1.18.0-block
• Extensions enabled: N/A (occurs during extension setup)
• Provider & Model: N/A (configuration issue)

Additional context

Current code (ui/desktop/src/components/settings/extensions/utils.ts):

export function splitCmdAndArgs(str: string): { cmd: string; args: string[] } {
  const words = str.trim().split(/\s+/);  // ← breaks on all whitespace
  const cmd = words[0] || '';
  const args = words.slice(1);
  return { cmd, args };
}

Workarounds:

• Create symlinks without spaces
• Use wrapper scripts
• Manually edit config.yaml