refactor: cd() avoid arg mutation

[antongolub]

• Tests pass
• Appropriate changes to README are included in PR

[antonmedv]

Why this change?

[antongolub]

Aligns overload implementations across the code: replaces args mutations with a recursive call.

[Copilot]

Pull Request Overview

This PR refactors the cd() function to avoid mutating the input argument by using recursion instead of reassignment when handling ProcessOutput instances.

• Replaces argument mutation with recursive call pattern
• Adds explicit void return type annotation to the TypeScript version

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/core.ts	Refactors cd() to use recursion instead of mutating the dir parameter
build/core.cjs	Compiled JavaScript output reflecting the same refactoring changes

[Copilot]

The recursive call creates unnecessary function call overhead. Consider using a local variable assignment instead: const dirStr = dir instanceof ProcessOutput ? dir.toString().trim() : dir; then proceed with the rest of the function using dirStr.

Suggested change

	if (dir instanceof ProcessOutput) return cd(dir.toString().trim())
	$.log({ kind: 'cd', dir, verbose: !$.quiet && $.verbose })
	process.chdir(dir)
	const dirStr = dir instanceof ProcessOutput ? dir.toString().trim() : dir;
	$.log({ kind: 'cd', dir: dirStr, verbose: !$.quiet && $.verbose })
	process.chdir(dirStr)