[Refactor] Extract shared execution environment logic in system.ts

[gonzaloriestra]

WHY are these changes introduced?

The packages/cli-kit/src/public/node/system.ts file contained duplicated logic for preparing the execution environment (setting FORCE_COLOR and determining the cwd) across three different functions: captureCommandWithExitCode, execCommand, and buildExec.

WHAT is this pull request doing?

This PR extracts the shared environment and CWD setup logic into a new private helper function getExecutionEnvironment. It then refactors captureCommandWithExitCode, execCommand, and buildExec to use this helper, improving maintainability and reducing code duplication.

How to test your changes?

Run the unit tests for system.ts:
pnpm vitest run packages/cli-kit/src/public/node/system.test.ts

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes
• I've considered analytics changes to measure impact
• The change is user-facing — I've identified the correct bump type and added a changeset with pnpm changeset add

Duplicate check

I performed a duplicate check using git log --grep="\[Refactor\]" --grep="Jules" --oneline as gh is not available. No previous PRs were found targeting this specific duplication in system.ts.

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PR created automatically by Jules for task 9574303689973063028 started by @gonzaloriestra

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