[CLI] Error while loading credentialsConfig file

Hi, new to kubero but finished installing on our gke cluster and then tried to log in using the CLI on a different machine. Got this error:
```
➜ kubero dashboard
No config file found; using defaults
Error while loading credentialsConfig file: Config File "credentials" Not Found in "[/etc/kubero /home/diwank/.kubero]"
```

Login command:
```
➜ kubero login
No config file found; using defaults
Error while loading credentialsConfig file: Config File "credentials" Not Found in "[/etc/kubero /home/diwank/.kubero]"

? Select an instance
Create a new instance

? Enter the name of the instance : julep

? Enter the API URL of the instance http://localhost:80 : http://kubero.julep.ai

? Kubero Token :
```

To be clear: the login command exits successfully but no file is created inside those two directories and other commands fail with a different error message:
```
➜ kubero list
No config file found; using defaults
Error while loading credentialsConfig file: Config File "credentials" Not Found in "[/etc/kubero /home/diwank/.kubero]"
Get "/api/cli/pipelines": unsupported protocol scheme ""
```

Start with the CLI entry points used by `login`, `dashboard`, and `list`, then trace how the credentials config is loaded and written after login. Reproduce the missing-file error and verify that a successful login creates a credentials file and that `list` can use the saved API URL.

Written by the indexing model from the issue text.