[FEAT cloudctl] - Implement Viper for configuration management

[onuryilmaz]

[FEAT cloudctl] - Implement Viper for configuration management

Labels

• feature
• enhancement
• configuration

Priority

(Medium) I'm annoyed but I'll live

User Story

As a cloudctl user, I can configure the tool using environment variables and configuration files, so that I don't have to provide all flags every time I run a command.

Description

Currently, cloudctl relies heavily on CLI flags. Implementing spf13/viper will allow users to use a cloudctl.yaml config file or environment variables (e.g., CLOUDCTL_GREENHOUSE_CLUSTER_KUBECONFIG). This makes the tool more flexible and easier to use in CI/CD pipelines or AI-driven automation where secrets might be passed via environment.

Acceptance Criteria

• Integrate Viper with Cobra in cmd/root.go.
• Support cloudctl.yaml, .cloudctl.yaml, and environment variables.
• Ensure all existing flags can be overridden by config/env.
• Add a --config flag to specify a custom config file path.
• Update README.md with configuration instructions.

Reference Issues

None