fix(cli): add trailing newline to --help output

[LifeJiggy]

Issue for this PR

Closes#28606

Type of change

• Bug fix

What does this PR do?

Yargs --help output does not end with a trailing newline, causing the next shell prompt to appear immediately after the last line of help text on the same line. This is a cosmetic issue.

Fix: Append EOL to the help output string in the --help parse callback before passing it to the show() function.

How did you verify your code works?

• bun run typecheck passes (exit code 0)

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Found potential duplicate PRs related to help output trailing newlines:

1. PR fix: add trailing newline to help output #26374 - fix: add trailing newline to help output
   fix: add trailing newline to help output #26374

2. PR fix(cli): add newline to help output #28622 - fix(cli): add newline to help output
   fix(cli): add newline to help output #28622

3. PR fix(opencode): ensure help output ends with newline #28643 - fix(opencode): ensure help output ends with newline
   fix(opencode): ensure help output ends with newline #28643

All of these PRs appear to address the same or very similar issue: adding a trailing newline to the help output to prevent the shell prompt from appearing on the same line. You should verify the status of these PRs (merged, closed, or open) and determine if any are duplicates or if this is a regression that needs addressing.