[Phase 5] Landing page, polish & Vercel deployment

[ahmedfahim21]

Part of the Learnify 2.0 rebuild. Depends on #47.

Context

Ship it as a flagship portfolio piece: public URL, polished landing, documented architecture.

Tasks

• Landing page ((marketing)/page.tsx): what it is, live demo CTA, feature highlights (generative UI, mastery graph, grounded citations, tutor memory)
• Vercel deploy: maxDuration: 300 on /turn (fluid compute), Neon + Blob integrations, AWS creds + SUPERMEMORY_API_KEY as env vars
• Bedrock setup notes in README: enable Anthropic model access in the chosen region, IAM user with bedrock:InvokeModel* only
• README rewrite: product story, architecture diagram (session flow), screen recording/GIF of a live session, local dev guide, legacy/ note
• Loading/empty/error states pass, mobile layout sanity, Lighthouse pass on landing
• Seed a few public example topics for first-visit demos

Acceptance criteria

• Fresh incognito visitor on the production URL reaches a live generative session in under ~30s
• README alone is enough for someone to run it locally