fix: stop spawnCliCommand from re-printing accumulated output

[kwy404]

Description

Root cause: in npm_modules/cli/src/utils/cliUtils.ts, spawnCliCommand appends every data chunk to the stdout / stderr buffers and then, when quiet is false, writes the whole buffer to process.stdout / process.stderr instead of the chunk it just received. Every new chunk therefore prints all previous output again. With stdio: 'pipe' and quiet: false (for example installAndroidApk and startAndroidActivity in deviceUtils.ts, which run adb install and adb shell am start), a command that writes first and later second shows first first second in the terminal.

Fix: write only the received chunk (data). The accumulated buffers returned in CommandResult are unchanged.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• Documentation improvement
• Performance optimization
• Test improvement
• Other (please describe)

Testing

• Tests pass locally (bazel test //...)
• Added/updated tests for changes (if applicable)
• Tested on multiple platforms (iOS/Android/Web/macOS as applicable)
• Manual testing performed (describe below)

Testing Details

Added src/utils/cliUtils.spec.ts, which runs echo first; sleep 0.5; echo second through spawnCliCommand with 'pipe' and quiet: false, and checks what was written to process.stdout.

Before the fix:

Expected 'first
first
second
' to be 'first
second
'.
1 spec, 1 failure

After the fix:

1 spec, 0 failures

npm test in npm_modules/cli has no new failures, and eslint and prettier pass on the changed files.

Checklist

• Code follows project style guidelines
• Documentation updated (if needed)
• No breaking changes (or documented in description)
• Commit messages follow conventional format
• No secrets, API keys, or internal URLs included

Related Issues

None.

Additional Context

Two lines changed in cliUtils.ts, plus the new spec.

[github-actions]

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