Refreshed outline settings with cleaner navigation

• Outline settings UI refresh: renamed "Brief" tab to "Overview", tighter typography and spacing, scrollable sections, and a single unified "Add" button for empty sections.
• Outline versioning simplified: version dropdown now shows version numbers and "Latest" without per-version metadata clutter.
• Hide outline "Add" buttons while the chat is loading or streaming to prevent conflicting actions.

Research settings now correctly accept values that exactly meet the minimum length (e.g., 3 or 10 characters) for Title, Welcome Message, Brand Name, and other fields.