v3 fish completions completion inside hidden commands don't work

[bittrance]

My urfave/cli version is

53ad542

Describe the bug

Fish completions only traverse into commands in cmd.VisibleCommands() so there will be no completions for anything "under" a hidden command.

To reproduce

	app := &cli.Command{
		Name:                  "mycli",
		Version:               "1.0.0",
		Usage:                 "Pure awesomeness.",
		EnableShellCompletion: true,
		Suggest:               true,
		Commands: []*cli.Command{
			{
				Name:   "more-awesome",
				Hidden: true,
				Action: func(ctx context.Context, cmd *cli.Command) error {
					return nil
				},
				Flags: []cli.Flag{
					&cli.StringFlag{
						Name:      "increase",
					},
				},
			},
		},
	}

Observed behavior

This gives no completions:

mycli more-awesome -- <tab>

Expected behavior

Reasonably, once you have entered the secret command, there should be completions again as normal. The bash completions seems to work like that.

Want to fix this yourself?

PR pending.

Run go version and paste its output here

go version go1.23.8 linux/amd64

Run go env and paste its output here

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/andqvi/.cache/go-build'
GOENV='/home/andqvi/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/andqvi/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/andqvi/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/andqvi/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.23.8.linux-amd64'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/andqvi/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.23.8.linux-amd64/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.23.8'
GODEBUG=''
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/andqvi/.config/go/telemetry'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/home/andqvi/projects/external/harness-cli/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build320049062=/tmp/go-build -gno-record-gcc-switches'