What this PR does

Before this PR:
The PinnedTodoPanel (agent todo list) always stretched to the full width of the chat area, ignoring the narrow mode ("伸縮對話框") setting.

After this PR:
The PinnedTodoPanel respects the narrow mode setting and constrains its width to 800px when narrow mode is active, consistent with the messages area and input bar.

Why we need it and why it was done in this way

The messages (Messages, AgentSessionMessages) and input bar (InputbarCore) are each wrapped in NarrowLayout inside their own components. The PinnedTodoPanel was missing this wrapper, so it was the only element that didn't respond to the narrow mode toggle.

The fix wraps PinnedTodoPanel in NarrowLayout at the same level as the other components in Chat.tsx, following the existing pattern.

The following tradeoffs were made: None — this follows the established pattern exactly.

The following alternatives were considered: Moving the NarrowLayout wrapper inside PinnedTodoPanel.tsx itself, but the existing convention is to apply NarrowLayout at the usage site (as done for messages and inputbar), so we follow that pattern.

Breaking changes

None.

Special notes for your reviewer

Single-file, minimal change. The import was reordered by ESLint auto-fix to maintain alphabetical order.

Checklist

• PR: The PR description is expressive enough and will help future contributors
• Code: Write code that humans can understand and Keep it simple
• Refactor: You have left the code cleaner than you found it (Boy Scout Rule)
• Upgrade: Impact of this change on upgrade flows was considered and addressed if required
• Documentation: A user-guide update was considered and is present (link) or not required. Check this only when the PR introduces or changes a user-facing feature or behavior.
• Self-review: I have reviewed my own code (e.g., via /gh-pr-review, gh pr diff, or GitHub UI) before requesting review from others

Release note

NONE