Summary: Added Eureka Math-aligned courses

Why It Matters: Khan Academy added new math courses. This means they are growing their math content.

What Changed:

• Removed "Math: Get ready courses" section from the main "Explore" navigation.
• Added "Math: Eureka Math-aligned" section with links for 3rd through 8th grade math.
• Added a new section about "Targeting Cookies" at the very end of the content.