Summary: Postmark's new MCP Server announcement

Why It Matters: This change shows a new product feature.

What Changed:

• The top banner changed from "Announcing the Postmark Challenge: Inbox Innovators $3,000 in prizes" to "Check out Postmark's new MCP Server! Try it out".
• The "iOS App" link was removed from the footer.
• The order of customer testimonials changed.