This PR launches the DevFlow marketing site

[craigcallen]

Summary

This PR launches the DevFlow marketing site and deploy pipeline on main, including a Vite/React landing page, waitlist capture, and production AWS hosting. It also tightens the messaging around MCP and product workflows, improves visual polish and SEO, and updates GitHub/README navigation to better support product discovery.

Changes

• Build the DevFlow landing page in Vite + React + TypeScript + Tailwind CSS v4 with the full marketing flow from hero through footer CTA
• Add Resend-backed waitlist signup via AWS Lambda function URL and remove unnecessary CORS handling in the Lambda
• Add S3 + CloudFront deployment via GitHub Actions, following the existing craigcallen.com pattern with PR builds, main-branch deploys, cache-control by file type, and CloudFront invalidation
• Rebrand the site with updated typography, colors, assets, and Font Awesome icons
• Improve product storytelling, especially around MCP’s zero-context advantage, DevFlow workflows, and skills
• Smooth section transitions and refine section flow/border treatment across the page
• Add SEO fundamentals including meta tags, structured data, sitemap, and robots.txt
• Rewrite the README as a product landing page, add light/dark logo handling, and point GitHub nav/footer links to the product README

Test Notes

• Verify the landing page renders correctly across key sections and responsive breakpoints
• Confirm waitlist signup succeeds end-to-end through the Lambda/Resend flow
• Validate PR build behavior and main-branch deployment via GitHub Actions
• Spot-check SEO outputs (meta, structured data, sitemap.xml, robots.txt) and GitHub/README link targets