fix(tui): omit NUL characters in clipboard writes

[fQwQf]

Issue for this PR

Closes#44198

Type of change

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

What does this PR do?

Shell tool output often contains NUL bytes, and the host clipboard rejects text containing NUL characters, so /copy failed entirely with "Failed to copy session transcript".

This strips NUL characters in the clipboard adapter (packages/tui/src/clipboard.ts) before the text reaches OpenTUI, so one stray byte no longer fails the whole copy — the rest of the transcript is copied as-is, which is the behavior requested in the issue.

How did you verify your code works?

Added a regression test in packages/tui/test/clipboard.test.ts: writing "a\0b\0" through the adapter now passes "ab" to the clipboard service. tsc/typecheck and oxlint pass.

Reviewer repro:

printf 'a\x00b\x00c\n' > /tmp/nul.txt
# let the shell tool cat /tmp/nul.txt in a session, then run /copy

Before: error toast, clipboard unchanged. After: copy succeeds, pasted text
is abc.

Screenshots / recordings

N/A

Checklist

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

[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

See CONTRIBUTING.md for details.

[github-actions]

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

Based on the search results, I found two related PRs that appear to address the same issue:

1. PR fix(tui): sanitize clipboard text #44197 - fix(tui): sanitize clipboard text
2. PR fix(tui): drop NUL characters before clipboard writes #44230 - fix(tui): drop NUL characters before clipboard writes

Both of these PRs are tackling the same problem as PR #44959 (your current PR): removing NUL characters from clipboard writes in the TUI to fix the clipboard paste issue. These are likely duplicate attempts to fix the same underlying issue (#44198).

[fQwQf]

Closing as duplicate of #44197, which implements the same fix and was opened earlier. Verified the approach works on GNOME Terminal / Wayland with the native host clipboard backend.