Diagnostic warning incorrectly reports 'config install method is global' for native-only installs

Description

The /mcp diagnostics command shows a spurious warning for users who only have the native binary installation:

⚠ Running native installation but config install method is 'global'

Environment

• Claude Code version: 2.1.92
• Installation method: Native binary only (~/.local/share/claude/versions/2.1.92)
• Platform: macOS (Darwin 24.4.0, arm64)
• No npm installation present — confirmed via npm list -g @anthropic-ai/claude-code (empty) and which -a claude (single result)

Steps to Reproduce

1. Install Claude Code via the native binary installer (no npm)
2. Run /mcp in a Claude Code session
3. Observe the System Diagnostics section

Expected Behavior

No warning should appear, since the native binary is the only installation and there is no conflicting global npm install.

Actual Behavior

The diagnostic check reports a mismatch between the runtime-detected install type (native) and a config-recorded install method (global), even though no global npm installation exists.

Notes

• The user's ~/.claude/settings.json and ~/.claude/settings.local.json contain no installMethod field — the 'global' value appears to be an internal default assumption
• The binary at ~/.local/bin/claude is a symlink to the native versioned binary, confirmed as Mach-O 64-bit executable arm64