Summary: Add Agentic AI to navigation

Why It Matters: This change adds a new topic to the main menu.

What Changed:

• Add "Agentic AI" link to the main navigation.
• Add "Discover AWS" to the main navigation.
• Add "Products" to the main navigation.
• Add "Solutions" to the main navigation.
• Add "Pricing" to the main navigation.
• Add "More" to the main navigation.
• Add "Feedback" link below the "Create account" link.
• Add a video player section.
• Add "How our customers are using Amplify" section with three customer stories.
• Remove "What Is Agentic AI?" from the "Learn" section.
• Change "What Is Generative AI?" link in the "Learn" section.
• Add "Your Privacy Choices" link to the footer.
• Add a chat widget with "Explainer" feature.