[Feature] Add sort by date/relevance option to Cloud Native Resources page

Current Behavior

The https://layer5.io/resources page displays cloud native resources (blogs, articles, tutorials, events, etc.) with no sorting option. Resources currently render in a fixed newest-first order by default (via the underlying Gatsby data query), but there is no visible "Sort by" control on the page, no way to switch to oldest-first, and no relevance-based ordering when a search query is active — results just show as a filtered subset in whatever default order the query returns, with no way for the user to know or change that order.

Desired Behavior

Add a "Sort by" dropdown on the Resources page with the following options:

• Latest — sort resources by newest first
• Oldest — sort resources by oldest first
• Relevance — sort by search relevance when a search query is active

This would improve content discoverability and help users find the most recent or most relevant resources quickly, instead of relying on an unlabeled default order.

Screenshots

Current state: https://layer5.io/resources
(No sorting option available)

Implementation

• Add a "Sort by" dropdown UI component near the existing search bar on the Resources page
• Implement sort logic in the existing Gatsby data layer
• Default sort should be Latest for best user experience
• Sort should work in combination with existing Type and Product filters

Acceptance Tests

• A "Sort by" dropdown is visible on the Resources page
• Selecting "Latest" sorts resources by newest date first
• Selecting "Oldest" sorts resources by oldest date first
• Selecting "Relevance" sorts by search relevance when search query is active
• Sorting works correctly in combination with existing filters
• UI is responsive on mobile and desktop