Show outdated content warning banner on FAQ pages if last_updated is over 16 months old

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As a reader, I want to be warned when an FAQ page may be outdated so I can approach the information with caution and confirm it through other sources if needed.

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🧠 Context

Some FAQ pages contain information that becomes outdated over time (e.g. admission requirements, course formats, deadlines). If a page hasn’t been updated in over 16 months, we want to display a global warning banner at the top of the page indicating that the content may no longer be accurate.

We already track update history using the last_updated frontmatter field.

This feature should be implemented on pages that use the layout:
layouts/_default/faq-question.html

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🛠️ Implementation Plan

1. Update the layout template

   • Open layouts/_default/faq-question.html
   • Add logic to check if last_updated is older than 16 months from the current date

2. Display a global banner

   • If the check passes, render a banner at the top of the page

   • The banner should say something like:

     ⚠️ This FAQ was last updated over 16 months ago. Some information may be outdated.

   • Style is up to interpretation, but it should be clearly visible and consistent with the rest of the site’s design

3. Test with a mock outdated page

   • Manually set an older last_updated value on a local FAQ page and verify that the banner appears
   • Test with a recent date to confirm that the banner is hidden when appropriate

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✅ Acceptance Criteria

• Pages using faq-question layout show a banner if last_updated is more than 16 months old
• The banner is clear, styled appropriately, and appears above the page content
• No banner appears if the last_updated date is within 16 months
• The logic is implemented inside layouts/_default/faq-question.html
• Behavior is confirmed by testing both outdated and recently updated pages