[BUG] Config mismatch warning with custom npm global installation path

Environment

• Platform (select one):
• [x] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: 1.0.67 (Claude Code)
• Operating System: Debian 12
• Terminal: GNOME Terminal
• Installation path: /data/repos/.npm-global/bin/claude
• npm prefix: custom directory (not default ~/.npm)

Bug Description

/status shows "Config mismatch: running unknown but config says global" when using custom npm prefix directory

Steps to Reproduce

1. Set custom npm prefix: npm config set prefix /custom/path/.npm-global
2. Install Claude Code globally: npm install -g @anthropic-ai/claude-code
3. Run /status
4. See warning in System Diagnostics

Expected Behavior

Should detect installation method correctly or not show confusing warning

Actual Behavior

/status command shows, under system diagnostics:

 System Diagnostics • /doctor
 ⚠  Config mismatch: running unknown but config says global

Additional Context

Claude works perfectly, warning is cosmetic but confusing for users