Add `magic` to the unified toggle-external.sh helper alongside gstack,
emil-design-eng, darwin-skill, find-skills. MCPs are toggled via
`claude mcp add|remove` instead of symlink moves.
API key loaded from $REPO/.env (gitignored) via .env.example template.
install-plugins.sh step 8.7 forces magic MCP off after each install run
so the MCP doesn't load into every session unless explicitly enabled.
Toggle: bash lib/toggle-external.sh enable|disable|status magic
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
