Improve the production landing page using the agentic prototype

[KalebCole]

Problem

The current GitHub Pages landing page is terminal-first and lists capabilities well, but it does not show the product's strongest agent-native outcome: turning a natural-language plan into a coordinated Partiful event with visible approvals.

Draft PR #92 captures that direction as a standalone prototype. Production should evolve docs/index.html from that concept rather than creating a second site.

Direction

Preserve the headline:

Your agent has the party covered.

Use the prototype's core interaction model:

• One natural-language event brief becomes a visible workflow
• Chat owns decisions, previews, and consequential actions
• The phone is display-only and reacts to event state
• Approval gates appear before publishing, inviting guests, or sending a blast
• The interface remains legible and useful without animation

Product-truth requirements

The landing page must distinguish three layers:

• Partiful CLI: deterministic event, guest, RSVP, contact, poster, and blast operations
• Bundled skill: command selection, sequencing, previews, approvals, and safety guidance
• Agent runtime: external venue/weather research, durable scheduling, wake-up, memory, and future execution

Do not imply that Partiful CLI contains a scheduler, workflow engine, research service, or notification daemon. Do not present an invitation API success as a delivery receipt unless the API exposes one.

Acceptance criteria

• Production work updates docs/index.html; no parallel landing-page surface
• Hero keeps “Your agent has the party covered.”
• Prompt-to-workflow interaction retains explicit publish, invite, and blast approvals
• Existing install, GitHub, npm, and quick-start paths remain prominent and accurate
• Supporting copy accurately separates CLI, skill, and surrounding-runtime responsibilities
• Desktop and mobile layouts preserve the bounded conversation rail and reactive phone model
• At 390x844, the full approval CTA and complete phone are simultaneously visible without clipping or overlap
• Keyboard interaction, visible focus, semantic controls, and reduced-motion behavior are covered
• GitHub Pages still deploys from docs/ through .github/workflows/pages.yml
• Verification includes automated interaction checks plus desktop and 390x844 motion captures

Out of scope

• Adding a workflow engine, scheduler, daemon, or persistent orchestration state to Partiful CLI
• Turning the phone mockup into a second control surface
• Expanding CLI scope to venue or weather research

Reference

• Prototype: prototype(landing): agentic Partiful concept #92
• Current production landing page: docs/index.html