Development record

04-surfaces/01-ahoy.md:41 and :1478-1481 say bare /abcd:ahoy mutates nothing, and :79, :1457 and :1526-1528 say the same of the dry run and doctor. Where ~/.abcd.noindex exists and holds no marker, the binary writes .gitignore and gitignore-laid into it before any command runs (layHomeIgnore, internal/surface/cli/homestop.go), so bare ahoy, --dry-run, doctor, --providers and credential each leave those two files. An absent home is not created. 05-internals/03-configuration.md describes the laying once but not that a read-only verb does it.