[BUG] Title: Chat input composer overlaps the last message, requires manual scroll to see it

[meirin0729-cpu]

Preflight Checklist

• I have searched existing issues and this hasn't been reported yet
• This is a single bug report (please file separate reports for different bugs)
• I am using the latest version of Claude Code

What's Wrong?

Title: Chat input composer overlaps the last message, requires manual scroll to see it

Body:
After sending a message and receiving a response, the bottom of the conversation is cut off by the input composer area, and I have to manually scroll down slightly to see the full response. This happens consistently, across multiple sessions/projects, and is not resolved by restarting the app, checking for updates, maximizing/resizing the window, or changing the OS display scaling.

OS: Windows 11
App: Claude Code desktop app
This has been a recurring issue over several days

What Should Happen?

「送信後、返信の全文がスクロールなしで見えるべき（メッセージが画面に固定されて隠れるべきではない）」

Error Messages/Logs

Steps to Reproduce

Claude Codeデスクトップアプリでメッセージを送信する
返信が返ってくる
返信の下部が入力欄に隠れて見えない、手動でスクロールしないと見えない

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

No response

Claude Code Version

2.1.158 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

関連: #58484, #60345（同じ症状、Mac版でクローズ済み。Windows版では見当たらなかったので新規報告）

[meirin0729-cpu]

追加情報：メッセージ送信時、Enterキーで送った時と、改行ボタン経由で送った時とで症状の出方が違うことがある。短いメッセージでも発生するし、発生タイミングはランダムに見える。長さとは関係なさそう。