Agent fails to launch when default permissions mode is set to auto

[codebutler]

Internal error: {
"details": "Invalid permissions.defaultMode: auto."
}

❯ cat ~/.claude/settings.json | jq '.permissions'
{
  "allow": [
    "WebSearch",
    "WebFetch"
  ],
  "defaultMode": "auto"
}

This mode was recently added, see:

• https://claude.com/blog/auto-mode
• https://code.claude.com/docs/en/permissions#permission-modes

[benbrandt]

Fixed in #501