feat(tui): add session search

[utsavsomaiya]

Issue for this PR

N/A

Type of change

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

What does this PR do?

Adds search for text in the current TUI session transcript. The search command opens a prompt, finds matching user and assistant text parts, scrolls to the selected message, and shows a compact toast preview. It also adds next and previous match navigation with keybinds.

How did you verify your code works?

• bun --cwd packages/tui test test/util/session-search.test.ts
• bun --cwd packages/tui typecheck
• Manually tested in the TUI with search, next/previous, and no-match queries.

Screenshots / recordings

Not included. Manual TUI verification performed locally.

Checklist

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

[github-actions]

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

[utsavsomaiya]

Inspired from @iamdavidhill, to create some opensource contribution 🫡

[github-actions]

Automated PR Cleanup

Thank you for contributing to opencode.

Due to the high volume of PRs from users and AI agents, we periodically close older PRs using automated criteria so maintainers can focus review time on the most active and community-supported contributions.

This PR was closed because it matched the following cleanup criteria:

• The PR was created more than 1 month ago
• The PR had fewer than 2 positive reactions
• Positive reactions are counted as thumbs-up, heart, celebration, or rocket reactions on the PR

PRs created within the last month are not affected by this cleanup.

If you believe this PR was closed incorrectly, or if you are still actively working on it, please leave a comment explaining why it should be reopened. A maintainer can review and reopen it if appropriate.

Thanks again for taking the time to contribute.