Active/focused element is incorrect on page load

• When a page loads with the AI panel collapsed, the body element gets the focus, which means that the main content panel cannot be scrolled up and down using the keyboard until the user specifically moves the focus within it.
• When the AI panel is expanded, the chat's textarea steals the focus, which also poses UX/a11y concerns as the user likely expects the main content area to be active when the page loads.

Resolution steps

• Remove (or make configurable) the autofocus behavior from Duo UI: feat(WebAgenticDuoChat): make autofocus control... (duo-ui!307 - merged).
• Ensure the product moves the focus to the main panel content on page load: Move the focus to the static panel on page load (!208176 - closed).
  • We're not doing this after all as we want the "skip to main content" element to always be the first focusable element, which should be sufficient. !208176 (comment 2809544279).
• When the AI panel is manually expanded, it should still focus the textarea automatically. !210507 (merged)
• The skip link should be the first focusable element: Ensure skiplink is first focusable element (!208203 - merged).