feat(TUI): add a button 'load previous messages' when it got its limitation

[PatricYan]

Issue for this PR

Closes #

Type of change

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

What does this PR do?

The TUI could only display the n(like 100)most recent messages per session. If a session had n+(like 100+ ) messages, the older ones were invisible and unreachable.

1. Open a session, see the 100 most recent messages
2. If older messages exist, "▲ Load previous messages" appears at the top with a count like "100 messages loaded"
3. Click the button or press e, 100 older messages load, scroll position stays stable
4. Repeat until all history is loaded, the button disappears when no more pages exist
5. No hard cap, the user controls how much history to load by clicking the button

How did you verify your code works?

run it locally to test

Screenshots / recordings

• image show the button

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]

Hey! Your PR title add a button 'load previous messages' when it got its limitation doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.

[github-actions]

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

[github-actions]

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