gplay CLI conventions (foundation)

Conventions shared by every gplay command; the normative source is docs/DESIGN.md in the CLI repo. --help wins over this skill when they disagree:

gplay --help                       # the whole command tree
gplay <group> --help               # a namespace (releases, tracks, team, …)
gplay <group> <command> --help     # one command, with its real flags
gplay exit-codes                   # the semantic exit-code table + diagnostic codes

Stability: the [experimental] banner

gplay is GA. A command whose --help opens with [experimental] sits outside the Public contract (pin an exact release in CI, the banner says so); every other surface holds until a major bump, so CI can pin v1 (stability).