fix(app): message list overflow & scrolling

[neriousy]

What does this PR do?

New messages were rendered outside viewport. Even more noticable when terminal was opened
Auto scroll fixes
Scroll to bottom when sending a new message

How did you verify your code works?

create a new session and send a message

[github-actions]

Hey! Your PR title Fix/session UI overflow 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]

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 my search, here are potential related/duplicate PRs:

Related PRs found:

1. PR feat(mobile): scroll-to-bottom button and touch UX improvements #9235 - feat(mobile): scroll-to-bottom button and touch UX improvements

   • Addresses scrolling and user experience for messages on mobile, which overlaps with the scrolling functionality being fixed

2. PR feat(tui): add auto_scroll configuration setting #7651 - feat(tui): add auto_scroll configuration setting

   • Directly related to auto scroll functionality mentioned in the current PR

3. PR fix: prevent user message box horizontal overflow on mobile viewports #6201 - fix: prevent user message box horizontal overflow on mobile viewports

   • Related to message overflow issues, though specifically for mobile viewports

The most relevant is PR #9235 as it also addresses message scrolling behavior. You may want to check if these PRs are addressing overlapping aspects of the same issue.