Ungraceful failure when `brev shell` connect

[brycelelbach]

This is a bad user-facing error message, we should make it something clearer.

$ brev shell mni-ml
2026/04/22 04:00:30.851230 WARN RESTY [error]
github.com/brevdev/brev-cli/pkg/store.NewAuthHTTPClient.func1
/go/src/github.com/brevdev/brev-cli/pkg/store/http.go:164
: [error]
github.com/brevdev/brev-cli/pkg/auth.LoginAuth.GetAccessToken
/go/src/github.com/brevdev/brev-cli/pkg/auth/auth.go:33
: [error]
github.com/brevdev/brev-cli/pkg/auth.Auth.GetFreshAccessTokenOrLogin
/go/src/github.com/brevdev/brev-cli/pkg/auth/auth.go:127
: [error]
github.com/brevdev/brev-cli/pkg/auth.Auth.GetFreshAccessTokenOrNil
/go/src/github.com/brevdev/brev-cli/pkg/auth/auth.go:160
: [error]
github.com/brevdev/brev-cli/pkg/auth.Auth.getNewTokensWithRefreshOrNil
/go/src/github.com/brevdev/brev-cli/pkg/auth/auth.go:331
: [error]
github.com/brevdev/brev-cli/pkg/auth.KasAuthenticator.GetNewAuthTokensWithRefresh
/go/src/github.com/brevdev/brev-cli/pkg/auth/kas.go:69
: error sending token request: Get "https://api.ngc.nvidia.com/token": net/http: TLS handshake timeout, Attempt 1
2026/04/22 04:00:30.856075 ERROR RESTY [error]
github.com/brevdev/brev-cli/pkg/store.NewAuthHTTPClient.func1
/go/src/github.com/brevdev/brev-cli/pkg/store/http.go:164
: [error]
github.com/brevdev/brev-cli/pkg/auth.LoginAuth.GetAccessToken
/go/src/github.com/brevdev/brev-cli/pkg/auth/auth.go:33
: [error]
github.com/brevdev/brev-cli/pkg/auth.Auth.GetFreshAccessTokenOrLogin
/go/src/github.com/brevdev/brev-cli/pkg/auth/auth.go:127
: [error]
github.com/brevdev/brev-cli/pkg/auth.Auth.GetFreshAccessTokenOrNil
/go/src/github.com/brevdev/brev-cli/pkg/auth/auth.go:160
: [error]
github.com/brevdev/brev-cli/pkg/auth.Auth.getNewTokensWithRefreshOrNil
/go/src/github.com/brevdev/brev-cli/pkg/auth/auth.go:331
: [error]
github.com/brevdev/brev-cli/pkg/auth.KasAuthenticator.GetNewAuthTokensWithRefresh
/go/src/github.com/brevdev/brev-cli/pkg/auth/kas.go:69
: error sending token request: Get "https://api.ngc.nvidia.com/token": net/http: TLS handshake timeout