What this PR does

Before this PR:
The ChatNavigation component at AgentChat.tsx:103 causes an unwanted horizontal scrollbar to appear in the agent chat messages container.

After this PR:
Added overflow-x-hidden to the messages container to prevent the horizontal scrollbar caused by ChatNavigation.

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

The messages container already had overflow-y-auto for vertical scrolling, but lacked overflow-x-hidden to suppress the horizontal scrollbar introduced by the ChatNavigation component. Adding this single utility class is the minimal fix.

The following tradeoffs were made:
N/A

The following alternatives were considered:
N/A

Breaking changes

None

Special notes for your reviewer

One-line CSS change — adds overflow-x-hidden to the agent chat messages container div.

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