fix(cli): add missing trailing newline to stderr output

[aslobodeniuk]

Issue for this PR

Fixes #33370

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Just adding a missing newline if it's not there. Yes the fix was done by the AI, and we can argue if it's the right place.
It could also be the missing newline in the actual "session" command, but assuming opencode is widely coded with AI (would be too ironic otherwise) the fix seems fair in a sake of "autoprotection".

If you paste a large clearly AI generated description here your PR may be IGNORED or CLOSED!

How did you verify your code works?

packages/opencode$ dist/opencode-linux-x64/bin/opencode session

Screenshots / recordings

Here's the screenshot of "after the fix" command and then "before the fix" command:

Checklist

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

If you do not follow this template your PR will be automatically rejected.

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

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[github-actions]

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

Potential Duplicate PRs Found

There are two related PRs that address similar trailing newline issues:

1. PR fix(opencode): add trailing newline to CLI help output #29898 - fix(opencode): add trailing newline to CLI help output

   • fix(opencode): add trailing newline to CLI help output #29898
   • Appears to address the same issue of missing trailing newlines in CLI output

2. PR fix(opencode): add trailing newline to help output #30547 - fix(opencode): add trailing newline to help output

   • fix(opencode): add trailing newline to help output #30547
   • Also addresses trailing newline issues in help output

Why they're related: These PRs all target the same root issue of missing trailing newlines in CLI output (stderr/stdout). The current PR (#33367) addresses stderr output specifically, while the older PRs address help output. It's worth checking if these previously merged fixes should have already covered this issue, or if this is a different code path that still needs the fix.

[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍