Respect KITOPS_HOME in library config path

[puneetdixit200]

Description

Add constants.ConfigPath() so library callers can resolve the KitOps root storage directory with $KITOPS_HOME support and the existing platform default fallback. The root command now delegates environment/default path resolution to that helper while preserving --config flag precedence.

Regression coverage verifies both $KITOPS_HOME and default fallback behavior.

Linked issues

Fixes #1171

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Tests

• GOMODCACHE=$PWD/.gomodcache GOCACHE=$PWD/.gocache go test ./pkg/lib/constants
• GOMODCACHE=$PWD/.gomodcache GOCACHE=$PWD/.gocache go test ./pkg/lib/constants ./cmd
• git diff --check

[puneetdixit200]

Addressed in f401174. The root command now delegates the shared environment/default path resolution to constants.ConfigPath() and only applies the --config flag override separately, so the same resolution is not duplicated in cmd/root.go.

[puneetdixit200]

The duplicate lookup concern is addressed in the current head: getConfigHome now applies the explicit --config override and then calls constants.ConfigPath() once for KITOPS_HOME/default resolution. I reran go test ./pkg/lib/constants ./cmd locally and it passes.