[BUG] Changing mode sets scroll position below chat window

## Bug Description

https://asciinema.org/a/CY6tOUVJpIOgCHPI

When I change the mode, either via shift-tab, or via `/plan`, my scroll position is set to below the chat window. I need to scroll back up to see the chat, but even then there are multiple chat windows.

## To Reproduce

1. Open a file in Neovim
2. Open Claude Code with `:ClaudeCode`
3. Type `/plan` into the chat window, hit enter
4. The scroll position is set below chat window

## Expected Behavior

I expect the scroll position to stay at the bottom of the chat, not below it.

## Environment

- Neovim version: v0.11.4
- Claude Code CLI version: 2.1.37
- OS: macOS 26.2
- Plugin version: v0.3.0

Setting `provider = "native"` fixes this.

## Additional Context

Whenever, I enter insert mode to type into the chatbox, the scroll position remains below the chatbox. This makes it impossible to see what I am typing or how Claude is responding.

Begin at the :ClaudeCode entry point and trace the mode changes triggered by Shift-Tab, /plan, and entering insert mode. Compare the behavior with provider = "native". Done means the view remains at the bottom of the chat, with one visible chat window and typed text and responses in view.

Scritto dal modello di indicizzazione a partire dal testo della issue.