[Refactor] Consolidate command execution in system.ts

[gonzaloriestra]

WHY are these changes introduced?

captureCommandWithExitCode and execCommand in packages/cli-kit/src/public/node/system.ts were manually duplicating the environment setup, directory handling, and error processing logic already present in their array-based counterparts, captureOutputWithExitCode and exec.

WHAT is this pull request doing?

Refactors captureCommandWithExitCode and execCommand to delegate to captureOutputWithExitCode and exec respectively. This centralizes the logic for:

• Setting FORCE_COLOR based on shouldDisplayColors().
• Handling the working directory (cwd).
• Performing checkCommandSafety checks.
• Configuring execa options like windowsHide.

How to test your changes?

Run any CLI command that uses these utilities, for example:
shopify app build

Duplicate check

Query: gh pr list --repo Shopify/cli --state all --limit 200 --search 'label:"Jules" "Refactor" in:title' --json number,title,state,url,body,files

Closest prior PRs:

1. [Refactor] Optimize copyDirectoryContents with glob cwd (aa120fb): Targets fs.ts, while this PR targets system.ts.
2. [Refactor] Use relativePath utility in copyDirectoryContents (9c19e7f): Also targets fs.ts.
3. [Refactor] Remove redundant Knip ignoreDependencies entries (b794124): Targets package.json.

This PR is meaningfully different because it focuses on unifying the command execution logic in system.ts, which hasn't been touched by previous Refactor PRs.

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

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PR created automatically by Jules for task 14120344445568562033 started by @gonzaloriestra

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