Use KUBECONFIG environment variable first

[Jancis]

This mirrors behavior of other cli tools where KUBECONFIG environment variable takes precedence for kubeconfig location.

[Copilot]

Pull Request Overview

Updates Kubernetes configuration handling to prioritize the KUBECONFIG environment variable over the default ~/.kube/config path, aligning with standard Kubernetes CLI tool behavior.

• Adds KUBECONFIG environment variable support across all Kubernetes-related commands
• Improves error messages to include the actual kubeconfig path being used
• Enhances error handling with file existence checks and non-fatal deletion operations

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
cmd/ciScriptsEsInitRemove.go	Adds KUBECONFIG env var support and improves error message formatting
cmd/ciReleaseWakeup.go	Adds KUBECONFIG env var support and fixes error message to include path
cmd/ciReleaseValidate.go	Updates kubectl commands to use --no-headers flag and adds error tolerance
cmd/ciReleaseList.go	Adds KUBECONFIG env var support with fallback to default path
cmd/ciReleaseDiff.go	Adds KUBECONFIG env var support and file existence validation
cmd/ciReleaseDeploy.go	Adds KUBECONFIG env var support and file existence validation
cmd/ciReleaseDelete.go	Adds KUBECONFIG env var support, file validation, and improved error messages
cmd/ciReleaseCleanfailed.go	Adds KUBECONFIG env var support, file validation, and changes fatal to non-fatal logging

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