体验：all-cli gh use 缺 hostname/user 只报 required flag，不说 list

User path

README documents:

all-cli gh list --json
all-cli gh use --hostname github.com --user <login>

A person who found all-cli gh from --help often tries the switch command first:

all-cli gh use
all-cli gh use --hostname github.com

Friction

Cobra prints:

Error: required flag(s) "hostname", "user" not set

That names the flags and then stops. It does not say where to read a host/login pair, and all-cli gh use --help has no example. all-cli gh list already prints hosts and accounts. The other context-switch commands (kubectl use, docker use, glab use, argocd use) now point at list when args are missing. gh use still does not.

Suggested change

When --hostname or --user is missing, return a usage line that includes the list command, for example:

want gh use --hostname <host> --user <login> (example: all-cli gh list)

Put the same example on all-cli gh use --help.

Start with the all-cli gh use and all-cli gh use --help entry points, then compare them with kubectl use, docker use, glab use, and argocd use, which already point to list. Verify the missing-flag path and help output; done means both mention the host/login format and all-cli gh list as the source of available pairs.