[BUG] Dangerous system-breaking sudo chown suggestion in `claude doctor` for Ubuntu users

Environment

• Platform (select one):
• [x] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: 1.0.98 (Claude Code)
• Operating System: Ubuntu 22.04 (WSL2)
• Terminal: bash

## Bug Description
The claude doctor command suggests a potentially destructive fix that can break
Ubuntu systems when npm global prefix is set to /usr. The suggested command sudo
chown -R $USER:$(id -gn) $(npm -g config get prefix) becomes sudo chown -R $USER:$(id
-gn) /usr which changes ownership of critical system directories.

## Steps to Reproduce

1. Install npm on Ubuntu with default configuration (prefix set to /usr)
2. Run claude doctor command
3. Observe the warning: "Insufficient permissions for auto-updates"
4. Note the suggested fix: sudo chown -R $USER:$(id -gn) $(npm -g config get prefix)

## Expected Behavior
The doctor command should provide safe solutions such as:

• Always recommend claude migrate-installer as the primary fix
• Check if npm prefix points to system directories before suggesting chown
• Warn users about potential system damage
• Never suggest changing ownership of /usr or other system directories

## Actual Behavior
The doctor suggests a command that expands to sudo chown -R $USER:$(id -gn) /usr on
Ubuntu systems, which would break the entire operating system by changing ownership of
critical system files and directories.

## Additional Context

• On Ubuntu, npm -g config get prefix defaults to /usr
• Running the suggested command would require system reinstallation
• The safe alternative claude migrate-installer works perfectly and resolves the

warning

• This affects any Ubuntu user following the doctor's recommendations